That's called "torquing" the bow. Which is a big nono. The first thing you need to do is adjust your grip (or how you grip the bow).

The grip should rest in the "webbing" of your hand between your thumb and forefinger. Your hand should remain open with your fingers either open or very lightly touching the front of the riser.

Check out this link for more info:
http://www.bowsite.com/bowsite/featu...grip/index.htm