Anyone dealing with horses of any size should know how to tie a quick release knot. If your horse starts to rear or pull aggressively against the rope you can quickly remove it from the post without fiddling with untying a knot.
1. Start by wrapping the lead rope once around the post.
2. Next cross one rope over the other.
3. Then take that rope and pull it half way up between the other rope and the post, making a loop.
4. Next make another loop through your first loop with that same piece of rope. The other end of your rope you will not be doing anything with, as it will be tied to your horse.
5. Pull it tight until you have a nice sized loop, being careful not to pull the rope all the way through.
6. Then you can make yet another loop through that loop.
7. Keep going until your reach the end of your rope or the desired amount of loops.
After you practice it many times you should be able to do it quite fast without even thinking about. To see if you have correctly tied the knot, pull on the end your horse would be tied to. No mater how hard you pull the knot should not budge. Now if you pull on the other end of the rope, the side you made your loops on, the rope should instantly unravel very quickly and you should not have to do any untangling.