Replying to Mac geeks! help me!

ok my mackbook pro has 111.2 gigs of disk space right now I have used 110.0 HOW!!!!!!!!!! what is this stuff taking up ALL f my disk space?!?!?! it is making my computer run at a snail pace. I need to know were all of this trash is that has no use to me and delete it. I have like 8 gigs of music and no movies and I guess I have a couple extra apps but nothing ridiculous. I haven't put anything on this computer to give it 40 gig. what is the stuff that is taking up all my space?and were I can locate and get it off my disk.