We have taken in a bulldog who is one year old. He lived with 3 kids under 7 yrs old and also another dog with whom he got along very well with. Our problem is that we think he was hit, never walked or even taken outside his own yard. He is very aggressive towards our dog (who wouldn't hurt a fly and is also trying to make friends with him with no such luck yet) Anyway, our dilema is how to socialize this dog with our own? He seems to be so scared and lost, he is an amazing dog who really needs some love and attention we just need him to be OK with our own dog? Any suggestions?

I am going to copy and paste from an answer I provided on another socializing thread.

Dog aggression is something that may never be cured, and you may never be able to have them together. But you can learn the triggers. Have you thought about obedience classes with all dogs for YOU to establish leadership? It's also a great bonding experience for you and the dogs. You need to teach your new dog, that he is not the leader of the pack. You need to establish this role. And simple obedience classes are a great way to get this point across.

When you have them together again, you want both dogs to expect "good things" to happen when they’re in each others presence. Let them sniff each other, which is
Normal canine greeting behavior. As they do, talk to them in a happy, friendly tone of voice
- never use a threatening tone of voice. Don’t allow them to investigate and sniff each other for a prolonged time, as this may escalate to an aggressive response. After a short time, get both dogs' attention, and give each dog a treat in return for obeying a simple command, such as "sit" or “stay.” Take the dogs for a walk and let them sniff and investigate each other at intervals. Continue with the "happy talk," food rewards and simple commands.

One body posture that indicates things are going well is a “playbow.” One dog will crouch with her front legs on the ground and her hind end in the air. This is an invitation to play that usually elicits friendly behavior from the other dog. Watch
Carefully for body postures that indicate an aggressive response, including hair standing up
On the other dog's back, teeth-baring, deep growls, a stiff legged gait or a prolonged stare.

If you see such postures, interrupt the interaction immediately by calmly and positively getting each dog interested in something else. For example, if there are two of you, both handlers can call their dogs to them, have them sit or lie down and reward each with a treat. The dogs will become interested in the treats which will prevent the situation from escalating into aggression. Try letting the dogs interact again, but this time for a shorter time and/or at a greater distance from each other.

Here is a great link to look over, any other questions feel free to ask!

Introducing a Dog to Other Pets : The Humane Society of the United States