n00b question

Hi.. I got this older G3 imac sitting beside me, And the hard drive thats in it right now is blank, its not even partitioned yet. I dont have any mac OS disks, or else i would just install that on it. so I'm looking to put fedora core or ubuntu on it. but i cant seem to get any of the cds to boot, even when holding C down while rebooting. Can someone please help me? thanks in advance.

well, i figured it out the hard way lol... the linux installation discs i was using before werent made for the imac.. The ones i had to use were ppc compatible