how do you start a band?

You will need to get together with some folks who have a similar taste in musical style.

You will need to decide whether to do 'covers' (other people's music that you will learn and perform to sound the same as or similarly to the original) or to do 'originals' (your own songs that you will write.) Sometimes it's best to start with covers and begin introducing your own material. Remember, no band ever made it doing covers. You'll eventually need your own material.

You will then need equipment. Lots of it. Instruments, amplifiers, a mixing board, speakers, microphones.

Hopefully, you already have the talent and can play an instrument (or many, in fact!) and can sing (unless you're going to do instrumental music...)

Oh from there...there is so much more.

well first, make sure you have someone willing to write songs.

and.. you need to know how to play instruments, someone to sing, that crap.

after that.. well, ask to perform at your school. or just start playing outside at lunch for people.

just keep asking for places to play.