First you need to import them into your game. This is simple, find the import button and select character sets and select import. Next find the one you want and open it, select ok and its available. To us it, you obviously go to your database and select it under the hero's tab under one of the slots.

Im pretty sure this is correct, I haven't used RM2K3 in a while.

~ KAMAHAME---Oh shit it's happening again.... ~