Lynn,
Unplug all the drives except the one to which you want to install the OS and try it, again. Before that, shut the machine down and pull the power cord out of it. Open it up, remove the M/B battery, leave it out for a minute or 2, replace. Button it up, plug the AC cord back in & now go to my 1st sentence. You shouldn't need to get into the BIOS... should boot from the install disc, no matter; will have nothing else from which it can boot, anyway. Hit any key, etc, etc.
Cheers,
Drew