First of all, good for you for joining here and getting started! I'm about your height, and I would LOVE to weigh 160 right now! (not that that helps
you at all

). But it's good that you're getting a grip on your weight at your age, and not waiting until you're older to do it. If you can establish some healthy eating habits now, you'll be able to lose the extra weight and keep it off. Not to mention stay healthy!
There are many ways to start a weight loss program. Everything from Weight Watchers to counting calories (that's what I'm doing). Also, all the things Viola mentioned above are good suggestions.
I've seen a lot of teens have wonderful success on Weight Watchers. It's a very easy program to follow and teaches you a lot about nutrition and portion size.
Whatever you chose though, make sure it's a healthy, long term solution, not a quick fix.
Best of luck to you! See you on the boards..