II. Needs
So you have some food and a leash. What else could a puppy need? Well, the food does need to be high quality (save money on good food and spend it on later vet bills), but you also have to feed the right amount and feed at certain times. Put out only as much food as your puppy will eat at a sitting. Free choice food makes your puppy into a picky eater and he will not associate you with food arriving. Follow the recommendations on your dog food label as all dog food is a little different. When feeding little pup get him into the habit of earning it by telling him to sit and wait. Of course, he won't understand at first, but just like with going potty it will become a habit.
A puppy needs to feel secure and looked after, but also to learn to have fun so spend lots of time playing, wrestling, and doing tug o war with him. The enjoyment you both will get out of it will build a strong bond. Gradually he will learn who is the fun one of the family (usually children), who is the one to watch for cues (usually mom of the house), and who to really mind (usually the dad of the house with his deeper voice and stronger manners). But all three of those can be in one if he has only one human in his life.
Make sure that your yard is very secure, not only from him getting out but from other dogs getting in. He is small and vulnerable. Protect him like you would a child. In general never let him out without direct supervision (not from a window but someone out with him) and even then usually on a leash, unless involved in direct play. A lost puppy, a puppy hit by a car, a puppy attacked by another dog, a puppy stolen out of the yard, a drowned puppy, all happen and it does not need to. That would all be your fault. So watch him! If your puppy has joined a family that already has an older dog then care must be taken. The older dog will not be impressed with the puppy and will speak in very undeniably strong dog language to back off and stay out of his space. If puppy does not understand this a swift nip might ensue. Usually puppies come with a certain amount of social immunity that protects them from adult dogs but the older the dog the less likely he will be to want anything to do with puppy. Respect your older dog's space and keep puppy in line. NEVER leave the two together unsupervised. I have heard too many sad stories of puppy and big dog were let out into the yard and when the owner went to bring them back, puppy was dead. An older only dog might think the swiftest way to take care of a problem is to make it permanently gone. Protect the puppy! Respect the older dog.