How do I become a Jockey?

Good answers from the other guys - - I'll just add succinctly that you need to begin by first of all becoming a good rider - find a good English instructor and learn to ride. It will be a great benefit if you then eventually are good enough to become an exercise rider, and from there go on to get your jockey's licence. But you have to start at the beginning, and that point is being able to ride calm and obedient school horses.