Are you sure it is a CD ROM and not a DVD ROM?
Many of the new OS X Boot disks (and system restore) from Apple are actually DVD's.
When your computer is booting, hold the "option" key down, and all available boot systems will display on screen (it takes a few minutes). Select the appropriate book system from that screen.
If your disk doesn't show up, either you have a bad CD/DVD Rom or problems with the disk itself.