Need help with floor pans and rear floor

[freak812]

OK guys, Im new to redoing stuff..Only thing I have evere done was replace rockers in an 84 chevy truck, so bare with me.

Im putting a new floorpan and rear floor section in my 66, do I have to trim the heck out of these new parts to get them to fit right? I have already replaced the full outer rocker and the inner rocker..What do i need to do next..I have a good chunk of the floor cut out already...What do i do now???