Excercises for quick results.!?

So I'm 15 and weigh about 215 pounds I'm trying so hard to lose about 90 pounds during summer (I go back on September), and I really am serious about this ecause I'm tired of not fitting into all the cute clothes and my mom has to take me too a plus size store haha!, ( I settle my fatness with humor), and my parents don't let me out of the house so no outdoor activities unless it's in my back yard!,( my backyards all concrete), thanks I really appreciate it.!:)