How do i introduce a puppy to my agressive dog?

First, you take both dogs to neutral ground, like a dog park where the dogs havent yet "claimed their territory". Put them both on a leesh, and first let them just sit next to each other, and then let them sniff each other, if your agressive dog fixes on the puppy, or he starts to get tense you must act immediatly and bring the attention pack to you with a simple tug on the leesh (you only have 1-3 seconds until the dog decides to react). It is also helpful to use a sound to correct the dog like *SHH*. if the tug does not work, then nudge the dog with your foot, and it will snap its head back up twords yours. Once they get used to each other, the dogs will be fine together, but make sure you know what makes the aggressive dog tick so you ccan prevent it from happening. Always remember that you are in control of the situation, not your dogs. If your dogs do get in a fight, you can always get past it becuase dogs are forgiving animals, and rehabilitating an aggresive dog can be done with ANY dog!