New Computer Help

My friend just purchased a new computer off of Tiger Direct, but we had to put it together… which we did.
Well, we get power switch and reset button and all the bus cables and stuff plugged into one another, and we go to install Windows XP.
…It says the disc isn’t in when we try it. Just gimme a list of things to do. We’ve tried both CD drives that he has… the DVD drive and the CD drive, and neither works.
I’m hoping someone like DS could gimme a list of things to try on thursday when I go over there again.
Edit: maybe I should be more specific >>
We get past the loading screen, but for some reason it loads all the Windows install stuff, but stops after we hit F8 on the install screen (the part where it says “F8=I agree ESC=Exit F3=Exit Setup” or whatever.)