How do i gain weight? Have tried almost everything i can....?

You have problem with your weight. First thing you should know is what is the required weight for you. I mean you must check your BMI (Body Mass Index) first and then determine how much weight you should gain. A good way of gaining weight is to eat banana with milk every morning. And you don't need to worry because this is your growing age and as you stop growing you will begin to gain weight. According to researches it has been found that simultaneous process of growing and gaining weight occurs 10 in 100 so if you are fat your height will increase slowly and if you are thin your height will increase rapidly and when it stops increasing your height you will surely gain weight.