Try getting her to jump up onto things first, it is more natural than jumping over. Once they get the idea that there are delicious snacks to be had if they make a blind leap you can get her to do this over the jump. You should put a towel or blanket over the jump so she has to jump it and cannot go under.
Use a command, just like you would to train a dog to jump.
P.S.
I hope you know what you are getting into.
I foolishly encouraged my ND to jump and now she hops onto chairs and onto the table and then across to the counter where she leaves little 'bunny berries' for me and chews the wire of my mothers $300 mixer :x
I use to put her in a wire play pen that is 30" high, but she easily clears it and romps around the house and yard. Thankfully she is trained to return to her cage when I call and I have since built a rabbit roller to keep her confined when outside. When loose in the house I must keep a very close eye on her.
