How do you make a horse rear?

I have tried everything and he just wont rear.

http://www.wikihow.com/Teach-Your-Horse-to-Rear-While-Riding

be careful. rearing should be the absolute last, hardest trick you teach your horse, because it can be hard to control once he knows how to do it. also, make sure to only do it on solid, safe ground, preferably when a trainer is around. this isn't a trick like bowing that an inexperienced rider should take on alone, it's a very experienced move.