You'll have to start out from the ground first.
This is how I've always taught it:
From the ground, you'll use your hand to "Poke" or "prod" the horse where your leg would touch. For for the haunch turn, you would prod on the front half of the horse. If he moves off, keep prodding until you get one step of him just moving his front and keeping his butt stationary. Make sure he's crossing his legs over as well, and reward him. Same thing with the forehand turn. But remember, horses are right and left brained. If you teach it on the right, the horse most likely won't respond to it on the left unless its been taught to the left as well. So make him step over to the right, then step over to the left, right, left, right.....But mix it up, too. Don't let him turn into a drone or get bored with the excersize.
As he gets more comfrtable with stepping over, gradually ask for more and more steps. And then once he's mastered it from the ground, get in the saddle and try it. :)
Pssh.I didn't pick up the wrong lead
It's called a counter canter...
...A very advanced maneuver.