I want to be more buff... help plz..?

Ok im only 13 and weigh 92 pounds... im maybe 5,5 and im going to highschool. How should i work out becuase im kinda scrawny.... and skinny.. Should i eat more? sleep more? work out more? what kind? push ups? how do i broaden my shoulders because i look small even thoguh im kinda tall.... idk. help?