I am hosting a few sites for my friends on the Wordpress appliance - I first downloaded and configured it last fall.  Now a couple of those folks are asking for the ability to edit their sites, which I am fine with, but I have been suddenly cast into an area I don't know enough about.  How can I set up SSH / SFTP for different users and lock them into a specific directory tree?  I haven't found a consistent set of directions, which tells me it is probably rudimentary enough that i should probably be able to figure it out.  Alas, I am a Windows guy trying to make the transition.  Any guidance?

Thanks - Tom