I have a slightly different way of thinking then English_Cowgirl, yet everyone does things different. Maybe you can take a bit of everyones idea here and use it with your own.

Jumping is a natural ability in a horse. You don't really need to "teach" the horse how to jump, it just comes natural. I have taught a few greenies and I do start with ground poles. I will set 4 ground poles in a row and have 1 pole between the jump standards. Once he is moving over those with no problems. I will put a tiny tiny tiny X. When he gets to that x, I will give him leg, encouraging him to pop up and over instead of just jogging over it. Make sure to give him most of the rein, you want to have 0 contact with his mouth while he is learning to go over the jump. If he decides to stop, make him at least walk over it. Do not, pull him away from the jump and start over. The last thing you want him to do is think that stoping is OK and he wont have to go over it if he does stop. I also, do not focus on any distances. I let the horse figure out where he needs to jump from to get himself over that fence. As they progress and get better, I will then start to help him find his distances if needed and will also start adding slight contact with his mouth.