Answer questions about weight loss please???

Ok I'm 13 and I want to lose about 30 to 50 pounds over the summer wich is a little under 3 months. What should my schedule be? Can I still play video games for afew hours a day as long I as excersize and eat right? How long should I excersize everyday? how should I excersize like what should I do? And how long will it take to lose this much weight?