Welcomes!

Oh man, weightloss is really an interesting experience! A journey to becoming a healthier person. That may not be your intention now, but you'll come to find the only real way to lose weight is to become healthier.
Since you're new to all this, take it slow. If you eat a lot, don't randomly start eating half of what you used to, because you won't stick to it. Same goes for exercise - you can't just start running 10 miles a day. You'll have to slowly work your way into it. Some people will lose weight faster than others. Admittedly, weightloss starts out easy, but eventually it'll get more difficult, but you can't let that discourage you!
Think of it like this: there are some people who aren't built to gain weight. They're just always thin no matter what they eat. You can be envious all you want, but guess what? They might not be living healthy like you will grow to be. If they aren't exercising and eating right like you'll start doing, then they're the ones who'll be weak and get sick all the time, and such, even though they're lighter than you.
You'll get discouraged and make mistakes. But here, you'll get all sorts of optimism and encouragement, and it'll really help.

It'll take time, but you can get there, as long as you don't give up.