Lose 30 pounds fairly quick?

I'm a recovering stoke patient. When I was in the hospital I after my stoke 2 years ago I gained 20 pounds. I need to lose 30 pounds. I'm 4ft9in and 15 years old. Physical activity is difficult but I can do it. Does anyone out there have any experince with major weight loss? What did you do and how long did it take you to loose your pounds? Also can anyone give me a step-by-step guide to lose 30 pounds. Another thing is that i don't have a lot of money. Serious help is appreciated.