Okay thanks for the advice ^_^
Barb135- your comparison of rocks to muscle and feathers to fat was perfectly said!
Muscle doesn't "weigh more". A pound is a pound, whether it's muscle or fat. Muscle is denser than fat, so the pound of muscle takes up less space than the pound of fat.
Compare muscle and fat, to rocks and feathers, with the muscle being equal to the rock and fat being equal to the feathers. You can have a relatively small rock that weighs a pound because the molecules are packed to tightly together; whereas the pound of feathers is big and fluffy, because the molecules aren't densely packed. That's equivalent to the fat... fat molecules aren't packed tightly, so the pound of fat looks larger.
By exercising you build muscle, which takes up less space in your body than the fat, so you look much smaller, though it may actually take a while to lose the weight... remember a pound is a pound, so replacing a pound of fat, with a pound of muscle will leave you weighing the same for a while, but then muscle burns fat, so eventually, you'll start losing weight.
Check your measurements before you start exercising and check them periodically to track your progress. Even if you don't initially lose weight, your body should get smaller because you'll be getting rid of fluffy fat.
All of that said, make sure your goals are reasonable before you start losing weight. "Skinny and thin" are not equal to healthy. You're very young and your body isn't fully developed, so you have to be careful of how much and how you lose weight. You need to talk to your parent/guardian and get their help in any weight loss effort.