How can I lose weight specifically in my situation?

Well, I've decided to take my life into my own hands now and get off my lazy butt every now and then. I am a 5'9 ish teenager who hasn't grown completely yet, but my problem areas are my stomach and my thighs, while my ares of strength are my core and my lower legs. I weigh approximately 165 pounds, and my target area is 115 pounds. Yes, a teenager losing 50 pounds doesn't seem very possible. However, I am willing to give it everything. I am so sick of being teased for my weight and how naturally slow I am. I have a treadmill and plenty of space to run outside available, and I would absolutely love to get to 115 pounds in less than a year. What should my diet be, how many calories should I be taking in, what exercise should I do-and how often? I just want a bit of a developed plan for the answer. Thank you so much- this is very important to me, and I thank you multiple times over for taking even the slightest interest! :)