Teaching a puppy to be confident and friendly towards others will help him live a calm and happy life.
A puppy needs exposure to other dogs. His owner should help him learn how to react and interact in the right way. Dog aggression is the result of a lack of exposure or bad experiences with other dogs. A frightened dog will bark and lunge at other dogs. This will send the other dog away which is exactly what the nervous dog wants.
Correct socialisation of a puppy involves him meeting and interacting with a range of dogs in a supervised way. Teach your puppy the release command so that when you are out and about he will know that he is free to play. This will prevent you from being dragged off to another dog that he wants to greet. Whilst your puppy is on the lead, encourage him to interact with another dog calmly. If he gets over-excited, lead him away.
Do not allow the puppy to play fight with other dogs as this is permitting unacceptable behaviour.
Begin training your puppy between 4-12 weeks. Enrol in a good puppy class where you will be guided correctly by the trainer.