Yes, she was in Pony club for years. We have an older mare she taught to jump, but just for fun, this one she wants to show so we want to be sure we do it correctly.
If she wants to show the horse, I would recommend you get a trainer to come and help her once a week or so. There are a couple of books that are good, 101 jumping exercises comes to mind, that will help you set up lines with related distances.
I have been so trying to find a trainer! We only have a couple in town and they are so inconsistent and never return phone calls. I may get her signed up for Pony Club again for some extra help. Thanks for the book suggestion.
I've trained my thoroughbred to jump and am currently training my mom's QH/Arab mare to jump...but that is with the help and supervision of a trainer. So I'm not an expert! But this is what we did with Bailey and are doing with McKenna:

We didn't really start with cabalettas because the horses already were comfortable with them, but do so if your horse isn't. Then, for quite awhile, we set up a very small x. Not something that was big enough to make them jump at all; just a low x. We practiced trotting over that...basically you're laying the foundation here. Some big things to focus on are, as I understand, making sure you are on a very straight line coming up to and away from the fence, as well as making sure to go over the very middle of the x. That part is basically just to get the horse comfortable going over an obstacle. From there we gradually raised the height, basically doing the same thing, until it was high enough for a jump, and so on and so forth. Don't get stuff too high too quickly, though, you don't want to over face a young horse.

That's probably where I would stop, or maybe before, without having a trainer to keep an eye on things and make sure no bad habits are developing. Another book I like is Jumping Problems Solved, Grid work: The Secret To Success, by Carol Mailer. It's got some good stuff for starting the young horse in there with canter pole grids.