I want to gain weight.?

I'm about 20 pounds underweight and I want to be average weight. I'm 15 and in school of course. I know I need a lot of calories, protein, and carbs. I'm having a hard time starting. Idk what to eat in the morning as well as the rest of the 2 meals (and snacks) what are some tips, as well as guides. I need some help and I'd really appreciate it! 15, 5"8 113 lbs