Go to your local shelter or humane society, they usually have several pit bull up for adoption. Speak to the staff and pick one that will match your lifestyle.
Contact a rescue in your area, just google pit bull rescues and find one in your area. There will be paperwork, an adoption fee and maybe a waiting period.
Go to your local animal shelter as these kennels are filled with dogs who need a good home. Make sure this is a breed your home-owners insurance will allow.