Just wanted to say: is that him in your pic? Oooooh, am I jealous! Gorgeous.
Ditto to everything said here. Current wisdom is that there is only so many good stops in a horse, so don't waste them trying to do a long beautiful slide when you are just learning. Save those for the show ring. Lessons, yes, you need some lessons!
Meanwhile, work on communication, ask for a stop by saying Whoa! in a clear firm voice first and dropping your heels and your weight into the seat at the same time. No rein. Try it a walk, try it at a trot until you get a consistent result. If he does not stop on the voice weight cues, pick up your rein, stop him and back him a few steps, then try again. Everyone's timing and cues are slightly different so he has to learn yours. Get some good reining videos and study the rider's position when they ask for a stop. Be sure they are good riders who get a stop with the horse in a rounded position with his front legs walking through the stop, no heads in the air or propped front legs!
Along with what FH said, the horse also has to be straight and increasing in speed when you ask for the stop in order to get a good long one. But you aren't ready for that yet! Work on correctness first, add speed later when you have a trainer.
Same with the spin. Work on slow correct spins before you speed him up. Again, study some videos. Most of us beginners pull back when we start to spin resulting in the front leg reaching behind to spin which will cause the horse to clip himself and get tangled up. It is a forward movement into the spin so he can reach across with his front leg to pull himself around. Try walking him in a small circle, making it smaller and smaller until you ask for a spin with outside leg at the girth and outside rein. Make sure your inside leg is OFF so he has room to move his shoulders over. Center your rein after he starts to spin but keep the leg on, most riders bump with the leg, not steady pressure.Your goal is planted back foot, a forward movement into the spin and a good clean stop. You can see if he planted his back foot because you will have a nice drilled hole in the dirt.
Enough for now, but I do believe if you start correctly and slow you will be able to add the speed later, it is very hard to add correctness if you are "pedal to the metal" from the beginning.
Have fun and let us know how you are doing!
