level floor

Hello! I am attempting to level my crawl space. It is filled with mainly dirt (also small rocks). It is sloped up toward the back. It looks as if someone started leveling it and left off. I've never leveled ground before....so I am wondering if I should just spread around what's in there...

I stupidly framed out my basement and put up drywall, which looks great. I then realized that I should level the floor - it drops 3-4" over 12' and it isn't flat, either. I want to use concrete to level the floor so that I have more flooring options. My drywall ends ~1" off of the floor so...