The training can be performed - up to a point - from the puppy's master, eg for the toilet. A dog can understand a lot of things from the tone of our voice. Each time a puppy performs something corectly has to be rewarded, however the treats have to be limited so that the puppy will not learn to do something only for food. The learning capacity of a puppy increases significantly after the 4th - 5th month, when it consolidates whatever it is learning. Bad habits have to be limited from the very beginning. However we must not try to change the dog's nature.
In the age of 4 months the puppy will change its teeth. During that period it will search for items to chew, which will help with the new teeth. Provide it with special chewing bones and discourage it from chewing your shoes! It's natural at that time the teeth not to be complete. Brush your puppy's teeth daily.