Starting an iMac 24" with remote keyboard

[Joe Lewis Wilkins]

Hi all,

A friend of mine just switched to an iMac from a PC and he called me  
to find out how to turn it on. Since I've never even seen  one except  
on the screen, I haven't the foggiest. Any of you know where the  
button is? I searched the Apple site and they assume we know how. He  
left his manuals with the guy who was transferring all of his files  
from the PC. That person is not available.

TIA,

Joe Wilkins