Not quite sure of some of the above points you make but hopefully this will help a little.

On a LAMP server you place all your web files (HTML, PHP etc) under /var/www (if using joomla etc you would use /var/www/joomla and so forth for Drupal and Wordpress ...).

If you wanted to run multiple websites on an unvirtualised server you would need to make new folders in /var/www and reference the address in a browser accordingly.

For Example lets say you have a home network with a LAMP server at the address 192.168.0.110 and you have 5 websites in 5 folders you would need to reference them as follows

192.168.0.110/folder1/ 
192.168.0.110/folder2/
192.168.0.110/folder3/ 
192.168.0.110/folder4/ 
192.168.0.110/folder5/   Where "folderX" is the folder you have created

If you dont have an index.htm(l) or index.php file in there you should see a default directory structure.

Alternatively you could create a virtual environment so that each website is isolated from the others (if you mess up one the rest will not suffer).

You can do this with some modest hardware and a home network. We have even created a new youtube channel that will have some videos shortly but a video is available HERE to setup proxmox (a virtual environment like described above).

I would suggest you get familiar with the command line and there are some great tutorials out there.

using the Apache config files, rather than using Webmin. Reading the Apache2 page of the Ubuntu Server Guide would be a good starting point (TKL v11.x is based on Ubuntu Server 10.04).

Personally what I'd do is start back at the start. By default your LAMP server will work as Chris described above - if you put your separate websites in subfolders of /var/www eg /var/www/site1 then they will be accessable via http://<ip-address-or-fqdn>/site1 - php pages load properly by default (ie not download - something you have done has messed that up, hence why I suggest to start again).

Now if I understand you correctly, ultimately you wish to have these separate websites appear when your browse to their specific domain or sub-domain? AFAIK that is called name-based virtual hosting.

If so, then my suggestion would be to create each site as a separate virtual host. To do that copy the default site file to each new site you wish to have. To ease future confusion I'd name these sites the same as the folders (in /var/www), something like:

cp /etc/apache2/site-available/default /etc/apache2/sites-available/site1

and so on...

Using this default config as a base, configure each file to use the relevant folder as the doc root (ie change /var/www to /var/www/site1) and you will also need to change the asterisk at the top to the domain name you will be using (ie change '*' to 'site1.example.com').

Then enable your new sites and disable the default:

a2dissite default
a2ensite site1
a2ensite site2
a2ensite ...
service apache2 reload

Now if you try to browse to your server using IP address then you should get an error. This is because the server will now only respond when you are browsing for your specifc sites.

The final all important step is to point your domain name to your server IP. For testing puposes it is quite ok to just add an entry to your local hosts file (ie the hosts file on the computer with the web browser you are testing from - check google for specifics on how to do it on your specific OS). If you are on the same LAN as the server then you canpoint the name to the server LAN IP instead if you wish. But don't forget to remove the host entries when you have finished initial testing.

Once you have that working as expected and want to take your sites live (ie for external access), then you'll need to configure the DNS of your domain name registrar to point your domain names to your (external) IP. Assuming that your server is running on a LAN - you'll need to configure either a DMZ or NAT/port-forwarding and/or firewall to allow the incoming requests to forward to your server. 

As each domain registrar does DNS config differently I can't really guide you here, other than to say that with your domain registrar you'll need to create an A record for each domain name which points to your external IP (most have a self serve web form to do this). If you do not have a static (external) IP then I'd suggest you get one. Otherwise you could make do with a Dynamic DNS provider (you can use the TKL Hub, or there is a thread somewhere here with extensive suggestions on providers).

In as much as they possibly can turnkey is as turnkey as turnkey gets!

When testing web servers I rarely have to use webmin. Sometimes I install a few packages like curl but I use putty to ssh into my server for that.

In regards to a tutorial I created a quick overview of using containers in proxmox not long ago.
I am currently working on professional versions and will be posting them to youtube to link into the newly created turnkeylinux channel.

Download the above video and give me your feedback if I could make it better!

Questions posted

1. when I open the interface, the first thing I see on the top left iss the view: no idea when each is appropriate
2. then there's a "Datacenter" node on top; what's the concept behind it, and how does it tie with the rest (I see a hierarchy under it)?
3. If I want to configure proxmox itself, like changing its IP, where would I go?

Answers

1. Assuming "open the interface" is refering to the proxmox web interface
   This needs some background first.
   Proxmox can be configured to have a parent node and child nodes (a cluster) so that the entire resource pool can be managed by one interface.
   I think your confusion comes because you are looking at a single server where the views are handy for clusters of servers showing certain resources on one interface.
   The different views are
   1. 
      Server view - Shows all servers in the cluster
   2. Folder View - Shows all resources in the cluster
   3. Storage View - shows storage in the cluster
2. Datacenter is the base hireachy ie it represents your "datacenter" so all resources naturally are a child of it. Your "datacenter" can be a single server or thousands of servers. Its whatever you define the parent and children as.
3. I have recently done this manually and do not know of a way to do it through an interface (anyone feel free to chip in here). The problem you will have doing this is that all the virtual servers running on the PVE you are modifying will have to have their IP addresses modified if you change the network class. This goes right into network theory and thats a big subject. A typical home setup (or class C network) will allow for 254 addresses. If you change the IP within this range and there are no conflicts you should be OK. If you change the IP to a different network eg going from 192.168.0.100 to 192.168.1.100 you must modify all the virtual servers accordingly.
   
   So how do you do it?
   You need to modify /etc/hosts file if your server is public (domain name etc) but on a home server you will need to at least modify /etc/network/interfaces
   
   To do this try running the following command
   nano /etc/network/interfaces
   Then again if your not used to linux the comand line may baffle you!
   
   Here is a typical one from a turnkey appliance (this is what gets modified when you run confconsole and modify the network)
   
   
   \# UNCONFIGURED INTERFACES
   # remove the above line if you edit this file
    
   auto lo
   iface lo inet loopback
    
   auto eth0
   iface eth0 inet static
       address 192.168.0.104
       netmask 255.255.255.0
       gateway 192.168.0.1
       dns-nameservers 211.29.152.116 198.142.0.51 211.29.132.12
    
   auto eth1
   iface eth1 inet dhcp

I agree to an extent that documentation is lacking in allot of areas.

Documentation is not everything though, forums are probably one of the best tools around.
After all you did get these answers from a forum.

Everyone starts off as a Noob! The last time I used Windows was 3.1, after which I switched to Linux because I needed to assign seperate IRQ's to the 4 com ports to run 4 modems at once. Necessity IS the Mother of Invention! So, I've been doing Linux for a long while. I even worked for Red Hat for several years, all without one day of formal IT study. I've blown things up more than once and that has been how I learned, more and more, while there is a LOT I don't know still.

Like Promox. I just kept my install CD handy and played with it until something borked. I re-installed completely and didn't do that mistake again, and so on. I've been steadily dinking with it for about 4 weeks now and I am just starting to get a firm grasp of the ropes. These forums have been a blessing and I wouldn't be this far without them.

But, I am familiar with Linux from the command line and coming straight from a Win environment has to be tough when the cursor is blinking at you and you're wondering what to do next. Just think of it as DOS on steriods. You'll dump your Windows desktop and install Linux in short order, as you catch on. 

Me, I haven't looked back, I haven't seen a beg screen or a time-out telling me that my trial period is about to expire, nada. No viruses, if you take resonable precautions. Welcome!! You'll survive. : \) Ric

I have a static IP address to my proxmox box, with a router intercepting it and set to forward to the localnet IP address of it. I want apache to send http requests to the Turnkey packages that are installed on it. Yes, they all have the usual 192.168.*.* addresses. I'll set my DNS A records, at Network Solutions, to the various hostnames I have on the Proxmox box, using the same static IP address and let apache handle sorting them out to their respective containers. Do I have it right so far?? Am I getting it??

Or, is there an easier way to do this?? I am NEW to all of this virtual stuff and I'm trying to get a handle on doing it correctly. Thanx!!!   Ric