It will not read because your iBook does not have a Super drive like mine. When you get an iBook, You have 3 options for it. cd read drive, DVD read drive, and the super drive which burns and reads cds and dvds. you must have the cd one because mine just reads cds and it makes a very loud noise, then slows down and spits it out. I read by apple that mine has a cd only drive. this might be your problem.
If you want it to read discs, you can:
Replace the cd drive with a super drive yourself. (only if you know what your doing)
or get a external dvd/cd drive reader. (Might be pricy)
Hope this helps! ~Sean