Hi, tips on teaching a horse to back up? He knows how to do it on the ground. He goes two steps but needs a lot of pressure on his mouth and cues and even if I sit way in the saddle he doesn't go back, I got this horse 1 week ago and he was a little spiffy on backing at the place but he wasn't bad, we just need to make it a little better.
All the mouth pressure in the world isn't going to improve your back-up. What you need to do with your hands is tricky to describe in words, but I'll give it a try. All you want to do is close the door, and that should take almost no real pressure. Assuming a snaffle bit (1:1 pressure ratio, no shanks), you want to have your reins short enough to take the slack out. No pulling, but no slack either. You're holding his hand. That is "neutral." To close the door with your hands, all you want to do is squeeze -- imagine the reins in your hands as two sponges, and you're squeezing the water out; no backwards pull required. I find that, with a curb bit (i.e., neck reining) a slight upward lift of the rein hand accomplishes much the same blocking effect, but I'd strongly recommend a snaffle until you both get really solid in the back-up if at all humanly possible.
Why no pulling? Because you want the horse to stay soft, round, and forward through the movement. Any degree of pulling is going to make him resistant and defensive about his mouth -- he'll gap his mouth open, crank his head and neck up and back, drop/invert his spine, and adopt a posture that is going to make it physically much harder for him to back up at all, much less do it promptly, smoothly, and comfortably. If he acts really confused, a slight pull might be necessary to help him focus backwards and get the ball rolling, but you need to make your point and go right back to that softly blocking hand.
Next thing is to think about your seat -- your weight distribution is honestly going to tell your horse more clearly what you want than any amount of fiddling with the reins will. What you want to do is use your leg aids to ask him to move forward, but use your seat and weight to direct that forward motion in a backward direction. Make sense? You're closing the door with your seat as well as with your hands. The best way I can describe to actually do that is to tilt your pelvis forward, putting more of an S-bend in your back. I've heard this referred to as a "******ing seat" by some folks. Contrast to a "driving seat," in which the pelvis tilts back, flattening the line of the back, which would direct all that wonderful forward energy ahead.
Upper body position can also make heaps of difference. Look straight ahead, even up a little bit, not down at his neck, and puff your chest out -- imagine that you're both just filling up with energy, and your hands and seat are gently directing it backwards. When he takes a step back, relax, stop your blocking aids (go immediately back to "neutral" hands and seat), and pet him like he just invented chocolate. Reward the smallest change and the slightest try. He'll surprise you with how quickly he improves.
Hope that makes sense and is helpful to you! Good luck!