how do you take apart a SAMSUNG MODEL: SGH-A737, and fix it?

Ok my phone has been screwing up alot lately  and i cant get a new one because they cost alot and i cant return it because i still have half a year to go with it. and i cant get it fixed cuz it still would cost alot, the economy sucks so i dont have any extra $, the screen goes crazy everytime i slide it shut and now the buttons decide when they wanna work or not. I totally wanna throw it at a wall but if i did that then i wouldnt have a phone at all, so how do i take it apart and reassemble it??? PLEASE HELP MEEEEEEEEEEEEEEEEEEEEEEE!!!!