If you would love for this image to be your reality, then teaching your pup not to bark now is vital. Because your Shih Tzu is still a puppy, barking is less likely to be an ingrained habit yet, and teaching him now to be quiet, rather than bark, will lay a foundation for him to be quiet for years to come.
Your pup might find barking itself to be rewarding, so it is very important to reward your puppy for being quiet instead. It is easy to ignore a dog that is being quiet, but remember to reward your puppy for that calm, quiet behavior so that he will offer it more often. Once a dog gets very excited about barking it can be hard for him to stop, so it is also important to interrupt your puppy's barking early by telling him something like "Aha". When he stops for a second then you can use that opportunity to reward him for being quiet. Doing this will teach him to offer the quiet behavior more often.
Many dogs bark simply because they are bored, and then it becomes a habit. The easier way to stop barking is to prevent it from becoming a habit in the first place. 'The Chew Toy Method' is best used for preventing bad barking habits from starting. By giving your pup something interesting to do that involves his mouth that is not barking, you are encouraging him to be quiet and to relax. He will learn over time to relax and to self-entertain with chew-toys when he is alone or bored.
If you use 'The Quiet Method' then it is important to praise your pup for speaking when you tell him to, but to only reward your pup with a treat when he is being quiet when you tell him to. This is so that 'quiet' will become his preferred command, and he will not bark in order to get a treat. When you tell him "Quiet" is is also important to sound calm and for your tone of voice to be soft. Even though it feels counter-intuitive, speaking softly close to your dog's ear is more likely to get his attention and to calm him down than speaking loudly is. If you become loud like he is, he is more likely to get excited and more agitated. After all, when you yell it seems like you are barking also.
If you are using 'The Quiet Method' or 'The Desensitize Method' then you will also need a small bag or a treat pouch. For both of those methods, you will also need an assistant, a front or back door in your home to practice at, and a leash. If you are using 'The Desensitize Method' then you will also need a location with other dogs and children, who are at a distance, a window that your puppy likes to look out of, and anything else that your puppy tends to bark at, to practice around.