Typically black is the ground. If you want to use a typical computer fan, you will need to buy a CPU as well. This is the computer's "powerplant". Or go to Radioshack and buy one of the bigger "muffin fans" made to be connected to one of the bare wire plugs that they sell. Just ask for what you need and they should be able to help. Any more questions, ask before you try, we really would hate to see you all crispy and not be a "man in black" but a "black in man".
~LM~
~LM~