How do you teach your dog agility?

Start with a chair and your dog on a down. If the chair is the correct height, he will not be able to stand under it. If you have a very small dog, find something else that is just a little higher than your dog when he is lying down to work with. Lure his nose under the chair with a treat. Let him nibble the treat but do not let him have the whole thing. Say, "crawl," and slowly draw the treat forward. He will have to crawl forward in order to keep nibbling the treat. When he'll willingly crawl under the chair for a treat without being lured anymore, you can stop using the chair. If he forgets to crawl, simply go back to using the chair a few more times to remind him what "crawl" means.