How to Put a Saddle On
Before putting a saddle on a horse, tie the horse to a solid object, brush away any debris on its back, and drape your saddle pad over the horse. If you are riding English, set the saddle on top of the pad and secure the girth around the underside of the horse by attaching it to the first and third billets like you would a belt. Alternatively, if you're riding western, place the saddle on top of the padding and then pull the front strap through the top and bottom loops on the other side of the horse until you run out of strap.
Tie your horse up to a solid object. Tie the horse's leader to a sturdy pole, fence, or another object that won't move. Leave at least 3 feet (0.91 m) of slack so that the horse can move its head or else it may injure itself if it gets spooked. Your horse needs to stay put while you attach the saddle to its back. If the horse is easily agitated, it may help to get a trainer that it's comfortable with to hold the leader while you put the saddle on its back. Use a bowline or quick-release knot to tie your horse up. Brush the hair on the horse's back to remove debris. Small pebbles and dirt can rub in between the saddle pad and the horse, which could agitate it. Use a horse brush to brush the hair on the horse's back. Move the brush with the grain to remove any dirt or small stones. Check for sores or raw skin around the area of the saddle to make sure that it isn't rubbing against the horse's skin. Place the saddle on the horse's back to make sure it fits. Put the saddle onto the horses back so that the front of the saddle lines up with the horse's withers, or front shoulders. Wiggle the saddle back and forth so that it sits comfortably on the horse's back.  An incorrectly sized saddle can injure the horse or become detached. There should be at least 3–4 inches (7.6–10.2 cm) of clearance between the horse's back and the saddle. If the saddle doesn't fit, you'll need to purchase a new one that fits better on your horse. Place the saddle pad on the back of the horse. Stand on the left side of the horse and line up the center seam on the saddle pad to the middle of the horse's back. The loops that hold your billets should be towards the front end of the horse. The front edge of the pad should line up with the horse's withers, or their front shoulders. The saddle pad should drape over the horse's back comfortably and naturally. Set the saddle on top of the saddle pad. Make sure that the horse knows that you're near it by petting its rear. Then, gently place the saddle on the horse's back, over the saddle pad. Wiggle the saddle back and forth so that it lines up right behind the horse's withers and sits comfortably on the horse. Tie the girth to the right side of the saddle. The girth is the belt that ties around the underside of your horse and keeps the saddle in place. Pull one end of the girth through the loops on the saddle pad, then attach them to the first and third billets on the saddle. Attach the girth to the billets like you would a belt. If done properly, the girth should now hang down from the billets on the saddle. There are typically 3 billets on each side of an English saddle. Attach the girth to the other side of the saddle. Walk around the back of the horse and pet the horse on the rear so that it knows you're near it. Reach down under the horse and pull the girth up to the other side. The girth should now be wrapped around the underside of the horse. Attach the girth to the other side of the horse. Pull the girth through the loop on the other side of the saddle pad. Attach the girth to the first and third billets on the other side of the saddle, making sure that the girth is tight against the horse, but not too tight or it will be uncomfortable for the horse. Pull on the saddle to make sure that it fits. There should be some clearance between the horse's back and the saddle and the saddle should not be pinching the horse's shoulders. Poke your fingers under the areas around the saddle to make sure they aren't applying pressure to the horse. If this is the first time that you're saddling a horse, ask an experienced rider to check to make sure that you attached it correctly. Place the saddle pad over the back of the horse. Drape a thick western saddle pad over the back of the horse. The front of the pad should line up with the horse's front shoulders, or withers. Western saddle pads are often much thicker than English saddle pads because Western saddles are heavier. Drape a decorative pad over the saddle pad. It's customary to place a decorative pad over the thick saddle pad that you initially put on the horse. Line the decorative pad or sheet so that it hangs down equally on both sides of the horse. This decorative pad is not necessary but may be more comfortable for your horse. Lift the saddle up and bring it down softly on the horse's back. Carry the saddle with both hands and stand next to the horse. Then, carefully lift the saddle up and over the back of the horse and place it on the horse so that the front of the saddle is facing forward. Western saddles are typically around 50 pounds (23 kg) so it's important that you lower the saddle as gently as possible so you don't startle the horse. Wiggle the saddle so that it sits comfortably over the horse's withers. The saddle should fit comfortably over the saddle pad. Once the saddle is properly positioned, push your fingers under the saddle to make sure that there are a couple of inches of clearance between the saddle and the saddle pad. Unhook the front and back straps so they hang down. Walk to the other side of the horse and pat it's rear end so it knows where you are. Make sure the saddle is properly positioned on the other side before unhooking the front and back straps to the saddle. Pull the front strap through the loop on other side of the saddle. Walk around to the other side of the horse, while petting its rear to calm it down. Reach down under the horse and pull the front strap under the horse and through the bottom ring on the other side of the saddle. Pull the strap so that it's tight, but not tight enough to restrict the movement of the horse. Thread the strap through the top loop. Pull the strap up through the top loop on the saddle and then pull it down to tighten it. Make sure that the saddle is still in the proper position and that it isn't pulling to one side of the horse as you tighten it. Keep wrapping the strap through the loops until you run out of strap. Loop the strap through the bottom loop again and then through the top loop. Alternate until you run out of strap. This process will tighten the strap, thus securing the saddle to the horse. Pull the top strap to secure the buckle. Once you run out of strap, pull on the top strap to push the buckle through one of the holes on the strap. This should lock it in place and secure the saddle to the horse. Attach the back strap to the back buckle. Reach down under the horse and pull the back strap up to the other side of the saddle. Don't pull the back strap so that it's tight or it will be uncomfortable for the horse. There should be enough room between the back strap and the horse so that you can fit your hand under the strap. Make sure that the back strap isn't too loose or your horse could get caught up on it while running. 
Tie your horse up to a solid object. Brush the hair on the horse's back to remove debris. Place the saddle on the horse's back to make sure it fits. Place the saddle pad on the back of the horse. Set the saddle on top of the saddle pad. Tie the girth to the right side of the saddle. Attach the girth to the other side of the saddle. Attach the girth to the other side of the horse. Pull on the saddle to make sure that it fits. Place the saddle pad over the back of the horse. Drape a decorative pad over the saddle pad. Lift the saddle up and bring it down softly on the horse's back. Wiggle the saddle so that it sits comfortably over the horse's withers. Unhook the front and back straps so they hang down. Pull the front strap through the loop on other side of the saddle. Thread the strap through the top loop. Keep wrapping the strap through the loops until you run out of strap. Pull the top strap to secure the buckle. Attach the back strap to the back buckle. 