Sprite collision

[Mekapix]

Hello, I'm trying to add gravity to this collision example but I can't think of how to do it. My main issue is applying gravity to the player character rather than the world as I added some lines so there's a world with gravity applied but it doesn't work with the character. I've tried binding the character to a body but I don't know where I need to actually place the code that'd allow me to do so. I've looked up quite a few tutorials as well but I can't seem to find any help.