First of all you must introduce them on neutral territory. That means outside your property.
Ask a friend of family member to have the pup on the lead and you have your dog on the lead.
Meet up somewhere and go for a walk together with the dogs so they can get to know one another. I suggest about an hour together before you go home together.
Always, always treat your black lab as the number one dog. Make sure you have separate feeding areas and the black lab eats first. Once they have both finished eating, pick up the bowls so there can be no fights. Dogs can be defensive over their food bowls.
Your lab will need to have time out from the new dog and we have found in our house that baby gates work brilliantly. This means that you can separate the dogs but they can still see each other and smell each other through the bars. You do not need to have total isolation unless one of the dogs is really misbehaving.
It is really important to keep the pack order when bringing in a new dog so as I said, the lab comes first in everything and never let the new dog push in when you are doing something with the lab. Jealousy creates problems.
I also suggest training for the new dog and maybe even the lab if required. General obedience training is very good to put in place and will help with any dominance challenges from the young one.