I got this off a website last year sometime and I haven't been able to find the website I got it from.
Sorry it's so long, but I kept the info because I thought it was extremely helpful
When to Start
At what age should horses start jumping? Your horse's breeding and upbringing will influence his physical maturity. While Thoroughbreds often reach full growth at 4 or 5, warmbloods may keep growing to age 6. Check with your veterinarian as to when your young horse's body may safely withstand the stress of jumping.
Whatever a horse's age, he shouldn't be introduced to fences until he accepts the rider's basic aids and stays relaxed and forward through simple schooling circles and turns. Jumping always reflects your horse's understanding of flatwork principles. If your horse moves reluctantly from trot to canter, for example, he's demonstrating that he's behind your leg. So how can you expect him to go forward and jump that scary coop in the field?
Play it safe and take your time with flatwork before introducing fences. If your horse seems immature physically or mentally, keep the fences very small until his body matures. No one ever got into trouble by moving too slowly when training a young horse to jump.
Ground Rails First
Before you begin actual jumping, teach your horse to quietly step over whatever is in front of him. Following a lead horse, let your youngster walk over a ground rail. If he wants to put his head down to sniff and look at it, that's fine; just don't let him turn away. Keep your leg on until he steps over the rail. Then praise him and walk back over the rail in both directions.
Once your horse has walked over the rail several times, try it without the lead horse. Then repeat this whole drill in trot.
Next, add a new rail 4 to 6 feet after the first; work over both in walk and trot. (Adjust the rails to fit your horse's stride.)
Incorporate ground rails into your daily rides for several weeks before you start jumping. Gradually progress to a series of three, then four rails.
Trot Rails to Basic Grids
Grid work teaches your horse basic jumping skills. The predetermined striding in a grid ensures that your horse will meet his fences correctly, building his confidence. Always start grid work with a single, low cross-rail, then progressively add additional low jumps, then increase height and width. And never feel you have to do all of these things on any given day.
Maintain a steady working trot and keep your horse straight as you approach and ride through each grid. Stay up in your two-point throughout the exercise and give effusively with your hands as your horse jumps. Let your horse figure out how to jump. Ride away from the grid in a straight line, then calmly direct your horse into a downward transition or a turn, so he learns to remain obedient after a fence, too.
Use three trot rails to set your horse up for each grid. Practice these alone first, then add a cross-rail, 9 feet after the last ground rail.
Ride through the exercise and react calmly to whatever your horse's effort may be. Stay quiet if he overjumps; add leg or voice as encouragement if he dawdles over the X.
Then add a second cross-rail, 18 - 19 feet after the first, and practice this several times. Make sure your horse stays straight through the exercise; you may need an opening rein in one direction or the other if your horse drifts sideways.
Finally, add a third cross-rail, 21 feet after the second, and repeat. Over time you can change the second and third elements to a low vertical; then add a back oxer rail to the third element. Grid work offers a safe, secure way to introduce height to your horse's jumping education. (Eventually you can add a fourth jump, 24 feet after the third.)
Some young horses progress to a three-element grid in one session. Others may need weeks of practicing a single cross-rail before they're ready to move on. Use your judgment, and any time your horse seems worried, slow down.
Grid work also enables you to work on any problems in your horse's jumping technique. If he drifts, set up wings or drift rails to keep him straight. Down the road you can alter both the distances and the number of elements within the grid. Shorter distances will encourage your horse to snap up his knees. Longer distances to low, wide oxers will help your horse use his back over fences.
Single Trot Fences
Intersperse grid sessions with work over single jumps. Set up two cross-rails. Add a placing rail, 9 feet before one of the cross-rails. (Adding a placing rail after the cross-rail, too, will keep a horse attentive and agile on landing.)
Incorporate flatwork into these early jumping efforts so that your horse learns to stay calmly on your aids between his fences. Trot the placing rail to the X, then ride circles and changes of directions around the little jumps, then repeat.
Now try the cross-rail on its own. Your horse should easily hold a steady trot rhythm all the way to the jump. If he hurries his trot at all, go back to the placing rail exercise. Work back and forth between the cross-rail with and without a placing rail. When this goes well, change the cross-rail to a small vertical.
Over time gradually introduce small, solid obstacles, like a gate or a plank. Someday your horse needs to learn to jump whatever you point him at. But for now, let him have a look. Taking an indirect path, walk up to the obstacle on a loose rein and allow him to stretch his neck down and sniff the jump.
Then take a lead from an experienced horse and jump the new obstacle, gate or plank. If your horse stops, he can look again, but this time he must jump from a standstill; don't let him turn away. Lavish praise on him when he jumps, so he'll feel like a hero, however hesitant he may have been at first.
The right moment to introduce cantering jumps depends on your horse's temperament and ability. Some horses need six months of trot jumps; others may begin cantering fences after six weeks.
Set up a cross-rail to a small vertical 60 feet (four strides) apart. Trot both jumps separately first; then trot into the line and canter out.
Because you've trotted in, your horse will add a step, covering the distance in five, rather than four, strides. You'll get a close distance for the vertical out. Adding the stride prevents him from getting strong or making a bid for the jump out.
In these early jumping lessons, seek exercises like this one that teach your horse to jump from the base of the fence. This way he'll learn to wait and use his body effectively as he jumps. Someday you can easily move up to bigger distances by adding speed on your approach. But if you allow your youngster to rush and "power jump" in these early sessions, you'll create a rushing problem that may plague your horse throughout his jumping career.
Play around with this trot-in, canter-out concept by setting up different lines of fences with varying numbers of strides. Then, after some weeks of practice, you'll be ready to trot a simple course of low jumps, approaching one or two fences on the course in canter. Return to a trot approach after each canter jump so that you're constantly reminding your horse to stay patient and wait to his fences.
Jolly Jumping (click here to learn the rules to jump by!)
If you're lucky enough to have access to some outdoor hunt-field type jumps, let your horse enjoy a few sessions of "jolly jumping." (Make sure your horse hacks quietly outside of an arena before you try this.)
Follow an experienced companion horse over small logs, coops or stone walls. Trot these if possible, but don't worry if your horse canters a step or two. After all, he's following his buddy out in the open and this is meant to be fun.
Stay quiet and centered in the tack and don't look for a perfect distance. Let your horse jump naturally out of his own striding; stay out of his way as much as possible. This sort of unstructured training gives your horse the chance to develop his own instincts about jumping.
Keep the Jumps Small and the Courses Simple
Even if your young jumper shows signs of stardom, stick to low jumps (2' - 2'6") and simple courses for the first year of his training. Give him plenty of time to think he's a superstar before you challenge him. Many young horses display jumping talent, but pushing them to jump too high, too fast, will inevitably cause them to lose heart.
Train your jumper progressively and slowly, however, and he'll learn to look for the jumps on his own. Someday he'll even save the day when you make a really big mistake to the jumps