How to improve vertical jump for a young beginner?

Calf raises are great, especially while holding weights. Don't jump up and down with weights on though, it will hurt your back. But, you can jump on a trampoline. Break down a jump. Understand what makes it work. When you do that, isolate those muscles with weight training. Go for height on that trampoline. Also, jump on the ground. Try to get height using nothing but shoes. Lastly, you have to want it. Every jump you do, mentally reach higher. If you're just jumping high waiting to jump higher, it won't work. You need that psychological need for a higher jump to make your brain make your muscles better. Try looking up when you jump and say "I need to go higher" eventually you will.

Invest in some 2.5 - 5 lb ankle weights and wear them during the day and at your practices, when you take them off for games, you will feel lighter than air and your vertical will increase dramatically. Running stairs is also a good way to increase the strength of your calf muscles and gives you more explosive power when you initially leave the ground. If you are looking for a weight program, focus on squats or use a leg press machine, work your thigh muscles and your calf muscles for the best results.

Plyometrics training is the sure way to improve your vertical. If youve never heard of plyometrics, its a specially designed jump training program that has a variety of workouts to "up" your jump. It includes jump squats, airborne lunges and other exercises that require you to get airborne. If this doesnt help you, nothing else will...

Everyone above has said great things about how to increase your vertical jump. I would like to add that doing frog leaps is a great exercise to increase your vertical jump. Start by squatting down and bring your arms back. Explode upward/forward and bring your arms up and lift your knees to your chest and as you land drop back down into the squat position. It will help out in the long run and you'll be flying in no time!