Im making some to my horse on the back after work just to make sure the muscles are good and it's relaxing him
Personally if I want a massage for my horse it's as a result of either some problem or my horse is working really hard and enjoys or will benefit from a massage :)
You must learn from someone-and Certifications are really the only way to do it right now. You must be taught feeling, there's no way to do this from a correspondence course and do it well...unless you are already a massage therapist.
Also, to do it well, you must know more than massage therapy-there're so many different things that can contribute to what is causing the horse to feel bad, that unless you learn many different crafts, you won't be good at it. This is why I have learned!