I have overcome obesity after being obese for several years. I am willing to help you. The best thing I can tell you to do is to start off small. Eliminate as many processed foods as possible from you diet, including packaged meals, chips, candy, chocolate, and dessert. Replace them with natural, nature-based food that you enjoy eating -- your favorites. Drink as much water as possible.

In terms of exercise, walking outside really helped me. I know sometimes it can be embarrassing but you can pick times like early morning or later in the evening when not a lot of people are out. Another thing which helped me was this Walk Away the Pounds dvd by Leslie Sansone. Good luck :)

I agree with always strong. Those are very good suggestions and will work if we are consistent with them most of the time. When we go off track just get back as soon as you can.
You already accomplished the 1st step in wanting to change. You are young, so now is a good time for food habits that will give you a healthy lifestyle.
My best to you....

Set small, short-term goals as well as your long-term goals. Reward yourself (with something other than food) when you reach each short-term goal.
It helps to have a circle of support. Posting here is a good start. You are very brave and smart to start your journey at such a young age. Focusing on you health and goals now will benefit you forever in your future.
You're going to do great!

make small goals, 60 to 100 is really huge for me anyway, say 20 lbs, then make a new one. go to a place like sparkpeople or fitnesspal on line helps set realistic goals meal planning even exercise.
dont beat yourself up, took all your life to get to this point, but with help and encouragement you will be on track and a beautiful loser!