Introducing a pit bull to other dogs and people

Question
Anne,
First let me tell you how well my 3 year old pit bull is doing.  6 Months ago I asked you for help on a timid dog that would poop in the house. The pooping in the house has stopped and when she goes outside she does her business in record time.
The bond has also improved. She will jump of the couch and on to the recliner and sleep on my lap for awhile without calling her.
But here is my question when we walk she really is not interested in any other dogs. On rare occasion the hair on her back will rise. How do I introducer to her own kind? With people she is usually shy, but once in awhile she will dart at them and usually women. Not sure if she wants to play or protect.

Answer
If you aren't sure of your dog's intentions, don't put anyone, dog or human, at risk.  Engage the services of an experienced trainer or behaviorist who is familiar with your breed.  Generally, puppies experience the optimal socialization period at age 8-16 weeks of age.  The dogs that aren't sufficiently socialized may have lifelong deficits in that area.  Pit Bulls that haven't been extensively socialized with other dogs, or have inherited a predisposition toward dog aggression, can be a danger, and it is the responsible handler's job to keep them safe from harm, and to keep others safe, too.  That doesn't mean that your dog does have ill intentions, it just means that if you can't be sure the dog is benign, you need help to evaluate that.
I'm so glad that your bond with this dog is improved, and that she has been so successful at her house training.  This is a smart breed, and even if she isn't social, as long as you protect her, you can look forward to many years of enjoyment of your companion.