Forget the "training collar" otherwise known as choke chains or prong collars completely. Stick with positive reinforcement and a flat buckle collar. Take a small piece of rope (or a very small leash) and attach it to the flat buckle collar and let pup walk around with it dangling. Don't let it be too long so that it gets tangled on everything and never leave it on pup in an unsupervised manner. He will get use to the dangling. Start out then with small walks in your yard. Let pup go where he wants with you holding onto the leash. Don't force where pup goes. Then slowly start to coax pup with treats to follow you. Before long he will realize the leash means walks and fun and not anything to be afraid of.

Good luck with classes. You will do fine!