Hello there,
I'm not quite sure what you mean but the character story is a biography for the character that you are choosing to make. This means that you should include the character's past experiences and important events that may have influenced his or her's decision to migrate into Red County. It can be as short or as long as you want it to be as long as effort has been put into it to demonstrate your role playing abilities.
I hoped this helped,
Tameson.