I am in grade 10, 15 years old and 6'1 3/4". I have big hands and can palm the ball...I could touch rim in grade 8 and getting closer to dunking everyday now..it literally takes no effort to touch rim now but whenever I go for the dunk I get the ball above rim easily but have trouble getting that wrist motion to actually throw the ball in the hoop...and help?

A common, low-tech plyometrics method is performing box jumps, where the athlete jumps repeatedly from the floor to the top of the box and back again. By concentrating on the mechanics of the jump, directing propulsion from the balls of the feet and thrusting with an explosive extension of the legs, the ability of the athlete to land lightly and immediately return to the floor enhances motor control over the movement.
The simplest method to measure an athlete's vertical jump is to get the athlete to reach up against a flat wall, with a flat surface under his/her feet (such as a gym floor or concrete) and record the highest point he/she can reach flat-footed (the height of this point from the ground is referred to as "standing reach"); fingertips powdered with chalk can facilitate the determination of points touched on the wall. The athlete then makes an effort to jump up with the goal of touching the highest point on the wall that he or she can reach; the athlete can perform these jumps as many times as needed. The height of the highest point the athlete touches is recorded. The difference between this height and the standing reach is the athlete's vertical jump.