My garage had extremely poor flooring. I've removed it and dug down 11". I plan to use a plate compactor on the dirt, add 4" of crushed rock, compact that, add 2" of sand, wet that, wait for it to dry out, cover it with plastic sheeting, and then I'm ready for the concrete layer.
Thing is, I don't know how to make a flat, high quality concrete pour inside. If I'm outside I can add forms around the slab and use a flat 2x4 or 2x6 to even the surface.
My garage is 25' x 20' and has a small stairway I'm not removing as a bonus obstacle.
How do I pour inside for best results and a flat surface?