First, set your bet using the slider. Then click one of the colored tabs on the right side to pick which color you'd like to designate as your 'correct' color for the next spin. It'll also spin the wheel. When you fail to land on that color, you lose the amount of your bet, but when you do land on it, you earn twice your bet!
Images from Google Code from me Idea from Hackingtons Background will be randomly selected each time you start the game