I would strongly suggest enrolling in a basic obedience or puppy kindergarten class. How old is your GSD puppy? If over 5 months then go straight to basic obedience classes.

One of the most valuable things any dog owner can do for their pup is to take them to a class as a puppy. Not so much for the dogs learning experience but for the socialization. I can not stress enough the importance of socializing in puppies. It is VERY IMPORTANT!

Along the way you will learn to teach your dog to sit, down, come, stand, and other commands as well. Find a class that teaches positive reinforcement.