That's a computer fan. Computer fans run on 12 volts DC. If you want to use that, you need to connect it to a 12v power supply that is capable of producing more current (amperage, A) than the fan consumes, but fans don't use much power, so almost anything you could find that's 12v would work. I only mention it to be formally complete. You can find power bricks at WalMart, Target, hardware stores, and Radio Shack, among other places. I'm not sure whether the fan's polarity matters or not when you hook it up.
Alternatively, I think you can get small fans like that which connect directly to household AC power, but if so, they're much harder to find. Good luck.