Multi site help

I looked through the forums and read what I found on multi sites and I'm just not picking it up.

I'm not much of a web person at all, I'm mainly a game programmer and I'm trying to set this all up so its easy and not time consuming to maintain.

So far everything's great, but now I'm trying to hook up multiple sites so I am basically looking for a walkthrough on how to make that happen. I tend to understand things quickly once explained, but I usually need a detailed explanation when learning something new like this.

If anyone has the time to help me out I would appreciate it very much.

Apologies if I missed a thread that has this already, and if it's covered somewhere else a link will suffice. Thanks in advance.