Spin: bump your horse right behind the front girth with your outside leg and (for beginners) lay your outside rein on their neck.
Slide stop: not sure, help?
Rollbacks: (for beginners) back them up lay the outside rein on their neck turn your hips to the inside and bump with your outside foot right behind the front girth.
Lead changes: I have several different methods from moving their hip up under them with your outside foot too tipping their nose the outside (a little), put your new inside foot forward, and bump with your outside foot further back towards the back girth
Speed changes: put your hands forward and sit up a little to make them speed up, sit more in your saddle (and for a beginner bump your reins to back them down)
Tell me if I have ANY of this is wrong. I have never watched a reining instructor or anything this is all what I have learned from 1, experience and 2, I teach these things to my barrel horses.
Thank you guys. (oh and if you have and good videos that would help, feel free)