i've always been taught to grip it like nirol described, but to absolutely NOT throw it like a baseball. Baseball players usually swing their arm like a trebuchet, letting the centrifugal power of the motion create force. Football quarterbacks have a much more piston-like delivery. Hold your arm back, elbow bent at nearly a right angle with the football on the side of your head level w/your ear and pointed towards your target. From 10-15 yards away from your target, snap your shoulder in a throwing motion and follow through w/your wrist. Make sure your fingers make the ball spin as it leaves your hand.
When you are practicing, try to remain conscious of only your fingers "flicking" the ball at the end of your delivery and a small point on your target. After a couple hours practice, your body will remember everything else for you.
This is the result of a well-spent youth.
Have fun.