I just bought a new dog but my other dog does not get along with this new puppy

Question
I have a dog that is 4 years old. It is true that he has been spoiled and he is not welcoming the new puppy that we got. He gets very aggressive when the puppy is around and whenever he tries to play with him. New puppy seems to be much more interacting and social while the other dog that I had for four years isn't. We left them in the fence when we were leaving the house, but the older dog was keep growling and showed aggression to the pup. I need to find out a solution to build better relationship between the two dogs. Can you please help me? I know that there should be a leader in the pack; however, what exactly do I have to do in order to build the order of their hierarchy?

Answer
If your older dog has never been around other dogs, it may take him a long time to accept this new dog.  There are a lot of dogs who seem to prefer to "pick their own friends" and don't easily warm up to other dogs.

I would first suggest that you never leave them alone unattended, or at least until you can see that the older dog is starting to accept the newer one.  You wouldn't want to come home to find there had been a dog fight and someone had been badly hurt.

I'm including some links to articles on dog/dog relationships.

http://www.ddfl.org/behavior/dog-intros.pdf
http://www.marinhumanesociety.org/Behavior/Handouts/PreventingAggression.pdf
http://www.marinhumanesociety.org/Behavior/Handouts/BreakingupDogFights.pdf
http://www.marinhumanesociety.org/Behavior/Handouts/CanineConfrontations.pdf
http://www.marinhumanesociety.org/Behavior/Handouts/MultipleDogs.pdf
http://www.marinhumanesociety.org/Behavior/Handouts/CanMyDogPlay.pdf
http://www.ddfl.org/behavior/canine-rivalry.pdf