Any kind of exercise that keeps you moving will work as well as maintaining a healthy diet. You should enlist the help of your parents, so they can make sure there are healthy foods available for meals/snacks, so you won't have to depend on junk food.
Well i can tell you one thing i did that made a big difference in my weight was refraining from drinking sodas! I also quit eating fast food. I lost 20 pounds from just doing this. I also like to do zumba and hip hop dance. You can look up zumba and dance workout videos online and do it in the privacy of your own home if you are uncomfortable dancing in a class situation. This is what I do. Also try to stay away from fried foods, candy, and chips.
If you really like fast food, try to eat it 1-2 times every 2 weeks . Drink LOTS of water. Just keep busy and stay moving . Instead of chips and soda, replace that with trail mix, fruits, and vegies.