TV,
Your diet produces very high insulin levels all day long which will predispose you to storing fat on your belly.
Eat only things that used to walk and grew out of the ground. Drink water. If it comes in a bag, a box, or a bottle (except the water of course), you probably shouldn't be eating it. If you have to order it from someone else, don't eat it. Simple.
Your bike riding is insufficient training for your lower body if you are trying to gain muscle. Learn to squat.
Seek consistency and structure to your day. Eat a specific times (before school, lunch, after school, evening meal, before bed) not when you're hungry. Exercise at a specific time, not when you feel like it. Follow an organized
training plan (there are many in the training forum) appropriate for your goals, training level, and experience.
Read about exercise for 15 minutes a day. Find a role model.
If you own a video game system, sell it. It makes you fat.
Don't worry about losing weight. If you follow the above, you'll get where you want to go.
Bill