Do a web search on BITE INHIBITION, and work on this with your pup.
A simple way to teach your puppy not to put teeth on you goes like this.
Get some small treats, little pieces of the regular food will do.
Feed the puppy a piece or two as you say, in a sweet tone of voice, "take it!".
Then close your hand over the rest of the food, letting the pup see it's still in your hand, and say, in the same tone of voice "Leave it!".
Wait until the puppy has not touched your hand for 5 seconds. Then immediately say "take it" and give the pup a piece of the food.
This teaches the puppy that he is not to touch when you say leave it. It works for most puppies very quickly.
Once the pup learns this, if he mouths you squeal OWWIE!! and say "Leave it!". Food reward with "take it" when the mouthing stops.
You will find more detailed info on your search on BITE INHIBITION.
Puppy class is a good idea as well, I always recommend people begin puppy training class no later than 16 weeks of age.
Good luck with your puppy.