I'm new here and need help gaining weight

I find it difficult to eat enough calories to gain weight every day.  I'm 13 yrs old, 5ft 8/9 in tall with a long and thin bone structure.  I'm looking to put on more muscle because I am a basketball player and need to be as strong as the other tall guys at my school.  When I'm at home I can't seem to eat enough to gain serious muscle, so what do I do when at school?

first of all make sure you are eating enough healthy fat to help you gain along with resistance training. things like peanut/nut butters, nuts, olive oil, lean meats, cheeses, yogurt made with whole milk, dense whole grain breads and bagels, soups made with lentils and beans, chili, starchy potatoes, brown rice, granola, and trail mix are a few things that are higher in calories and fat but still healthy. bring things like higher calorie protein bars to school to snack on (if you can) and wraps or sandwiches to school. peanut butter and banana or jelly sandwiches on whole wheat bread or bagels are great if you like them or things like turkey with cheese. drinks are an easy way to get calories up to aim for things like milk or shakes like boost and ensure. resistance training a few times a week will help you gain lean muscle not just flab. hope that helps!