The Common App generally requires a letter of rec from your counselor and one or two teachers. It may vary depending on the colleges you are applying to.
Be sure to give adults plenty of time -- pay close attention to all deadlines!
On the left, you will find links to a teacher and counselor "brag sheet." Fill these out and share them via email with any teacher/counselor who will be writing you a letter of recommendation.
If you're not sure which school to pick . . . let the schools pick you!