Peltiers suck amperage from PS's like nobody's business. Unless you have a mondo PS, ~400+Watts, it can be better to dedicate a different PS than you're already using to powering the Peltier. TEC's aren't at all insulted with a separate power supply of their very own. **Just be sure to turn on the Peltier's PS when you turn on your main PS!**
Do you want to know where to plug in the leads or what kind of power supply you need? You could try ebay and look for a 300Watt AT power supply for like 15-20 dollars. Or if you need to know where to plug the wires to black on the peltier is going to be ground and the red will be the hot wire. Plug the red wire to the yellow on the PSU connector and the black one from the peltier to the black wire next to the yellow wire on the plug. Well hope that helps.