Ok. I backed up Doom 3 using CloneCD and Alcohol 120%, but when i go to make sure it worked, I pop in the first disk, and the Doom screen comes up, then nothing.....Did I do something wrong with the backup of it? Please, help from anyone

You probable did nothing wrong. Only a few CD-writers are able to make perfect working copies. If your CD-writer can't do it you'll have to use either a cracked executable or create/mount a ISO image in a virtual drive to play it.