I agree with the above poster except for one thing, I wouldn't give equal attention. I would give more attention to the existing dog. Remember, you'll have the rest of the puppy's life to bond with him so just spend this time assuring your existing dog that this puppy will not take away any of your affection.

Also, you want to introduce the dogs on neutral ground. This may mean you'll have to go out of your way and introduce them at a nearby park, but even the street in front of your house is better than introducing them at home. There may be a few scuffles here and there but it's all normal and completely expected. Good luck! My dogs raised he** when I introduced Giselle into the family, but everything is fine now