As for introducing your Lab puppy to another pet at home, make sure to supervise and lay down the ground rules right away. If your new Lab puppy is meeting a dog, make sure you step between both dogs if there is any unwanted behaviour. This is called splitting. Don't let them sniff more then a few seconds before splitting so that both dogs know you are there to protect them.
For example: If you have a territorial dog, the Lab puppy needs to be protected from his bullying behaviour. A territorial dog is on guard and without protection for the puppy, you risk a possible accident. If you have a shy dog, the puppy and the exuberance of puppyhood may be too much and overwhelm the older, shy dog. He needs protection from the Lab puppy. You're telling the older dog: "I won't let the new puppy bug you too much..." and you're telling the puppy "I won't let the old dog hurt you." These are wonderful messages to give to your dogs!
Ideally, if they can meet somewhere neutral first, like at the end of your street or a friend's house, it helps in initial meeting. No one "owns" the neutral location and that certainly is helpful in aiding the first meet and greet!
In the case that you can not meet at a neutral location, you can let them sniff under a door way first. If the old dog barks step on the side the old dog is (without the new puppy) and back up the old dog away from the door, signaling that you do NOT approve of that kind of reaction. Do this as many times as necessary. If the older dog is not learning or responding to this process, there are a couple of options depending on why he isn't responding.
If it is a hyper dog them put him outside for a bit and maybe get someone to take him for a long run to settle him and get his mind off it for a bit.
If it is a scared bark then put the puppy on leash and let the older dog see the pup with the option of running away when he wants to, keep blocking the puppy from going to see the older dog so that the older dog knows you will keep him safe and at the same time the older dog can see him and get used to his scent. Shy dogs will remove themselves from the area, and we need to give them the opportunity to feel safe and deal with the new addition on their own terms.
Take your time if you are nervous, don't rush the meeting. You want it to be a good experience not a bad one. Go the extra mile for the first few days and keep them separated until the time is right.