If you're 14 you need dairy, and also a healthy diet so don't try to get fit by not eating, please.
Having said that, let's get to it.
If your goal is losing weight then just start doing weights (I know how it sounds, but you won't get big muscles, that's way harder than it looks) or anaerobic exercises like pull ups, sit ups, push ups, you get the idea.
This is how it works, by doing this kind of exercises your muscle activity increases and it keeps your metabolism up to speed for around a day and a half, even if you're doing NOTHING AT ALL, which means you can just do exercise for half and hour and do nothing the rest of the day AND the next day.
If you start doing exercises like running you will also lose weight, but not as fast or easy. Also by doing anaerobic exercises you will get sore muscles the next day, GUARANTEED, it sucks, I know... but you also get an increased mitochondria count per cell and increased ATP which means more energy all day long.
Won't get anymore into details, just exercise smartly and eat well.