First off, find an area that your dog is used to, and comfortable in with enough space. You can't really teach this trick if your dog is on a leash, so a good place to teach this trick is in a fenced in backyard or in the house. Remove all distractions in the area, like balls, toys, cats etc. Bring in your dog, treats, and hula hoop, and let your dog sniff around a bit and get settled down. Hold the hoop so the bottom touches the ground in one hand, in the other hold a treat on the opposite side of the hoop as the dog. Try to lead your dog through the hoop with the treat, only give him the treat if he goes through the hoop. Your dog should only be walking through the hoop at this point, not jumping.