Hi Chelsea (I just love that name)
At your age I would suggest that the most imporant thing that you do is to get moving. Walk, dance, start a weight-lifting program, swim, bike, learn a new sport... whatever. Women who adopt an active lifestyle in their teens and twentys will have a much easier time managing their weight later in life.
Everyone agrees that the very best exercise program is one you can stick with. And that is a very personal thing. So here's a suggestion: Compile a list of all the possible activities you can do, or have access to. For example if you do not have access to a pool, swimming is off the list. But be creative and do a little research into community centers, YMCAs, churchs, school, etc. Many have programs or activities at little or no cost. And then start trying everything on your list. Something is bound to stick, either because you find you love it, or you find you love the other people involved, or you have a special talent for it.
As they say... no time like the present. So let us know what is on the list!