How to hang/finish drywall?

Ok, my uncle started to re-due my grandma's house shortly before he moved out, well when my grandma ped away my mom bought the house, now I need to know how to finish doing what he started. So he started to hang drywall, and it's basically finished, but around the windows there is no installation, and no framing, how do I securely install all of this? I can't find anything on it, also is there a certain type of paint or finish you have to put on drywall before you can paint, and everything else, Thanks!