You go to your house (this can work in other places too, but going to your house is the
simplest) then go into the right room that has your bed, mirror, and drawer-thing in it.
Walk up to either the drawers or the mirror and press the a button. You can then change
your clothes. I like using the mirror because it has all the choices you got when you
first started the game. The drawers have clothes in them that I think you earned in the
game or something.