Try to stay away from the sweets as much as you can.try to have meals that have fruits and veggies and never skip a meal because if you do you will feel more hungry at the next and might over eat.eat your food slowly so you'll know if your still hungry cuz ate fast but still felt hungry and got another plate of food then when I stopped I felt over filled since the food in me didn't get to my stomach till I was done with the second plate and I felt full from the first plate then the second plate reached my stomach and I was over filled. Try to drink more water during the day it will make you eat less at the diner table if you eat slowly to you'll fell full with a tiny bit of food since there is so much water in your stomach.
I would recommend picking up a sport or two that will get your heart going and do something active every day. 30 mins to an hour of heart pumping exercise daily will show results in 3 to 6 months. The most important and long lasting results will come from a lifestyle change rather than focusing on loosing weight in your belly. Make sure to talk to your doctor and parents before starting any sort of workout plan, and stay focused. Be active every day.