ah, you need a switch.
find the power on jumpers and cross them with a small (wide enough to touch both of them) flat head screw driver. it only takes a quick touch to get it to turn on.
the power on jumpers should be listed in the manual or if you lucky on the mobo.
if all else fails, ... run it up and down the jumper bank. you'll hit the right one sooner or later
*note* i watched my friend do this for weeks beacuse he didn't have a power switch.