You can't turn on your computer with your keyboard to my knowledge.* You can wake it if it's asleep, but that's not the same thing. Looks like you're stuck searching under the desk for the power button.
*I'm sure if you put a USB switch and connected it to the power posts and connected it to a switch on your keyboard, you could power it on.
@badrobot has his daughter's computer hooked up to a big, red button that she can turn the system on and off with without touching the power button. It's work to do, but if you're up for it, I'd see if he could give you some advice.