My advice would be to take some lessons on your horse with a trainer that trains and shows reining horses. You can mess up his training very quickly.
You would not buy an airplane and try to learn how to fly it by yourself. It is not fair to this horse to try to 'invent it over' and teach yourself how to 'push the buttons right'. If he is a trained reining horse, someone spent a lot of time teaching him how to respond to each aid and cue. You do not want to mess it up.