Need to lose 50-60 pounds now, HELP ME?!!!!!!!!!!!?

Hi, i am 15 years old and am overweight heading towards diabieties and things. My doctor told me i need to lose weight because of my height and age while i am young and he said by december i need to lose most of it. I dont know wat to do and i have tried almost everythng u can think of. Somebody help me please with something that is free besides the groceries and that will help me get these stupid *** phat bulges be gone with. THNX