Whenever you throw the ball to another person, you should work on accuracy. For this reason, you should not throw to another person in this particular drill, since the entire purpose of this drill is to improve the "whip" and the strength of the quarterback's throwing arm. In this drill the quarterback should throw the ball just as hard as he possibly can, without concern about the accuracy of the throw.
Stand about 10 yards in front of the net, gripping the ball in your passing hand. Raise the ball high directly over your head with both hands, so that the quarterback's passing arm is straight up and down. From this position, throw the ball into the net just as hard as the quarterback can without drawing the ball either backward or downward prior to throwing. The quarterback must avoid the natural tendency to flex the elbow or to draw the ball back just before starting to throw. The quarterback must always remind himself to throw as hard as possible. With enough practice, the quarterback will eventually find that by whipping his arm down and snapping his wrist, he will be able to throw into the net with considerable power.