Relax your fingers and hover your hand over the touch pad. Visualize all of your finger tips casually coming together to a single point, but stopping just before they collide. Now drop your hand so that your finger tips hit the pad, save the pinky finger. now, open your hand up, fingers spread wide like you are about to stick your palm in wet concrete.
Behold, your desktop appears.
Oops I was talking about the spreading gesture.