C.A.
Hello B.,
I have two labs that my husband and I successfully "potty trained." A key thing that I learned was that if they have an accident in the house, it's our fault, not theirs...we didn't let them out. Also, constancy is key (the other post is correct).
What we did was go outside with them about every hour or hour and a half. We would stand in our yard and say "go pee" (you can pick whatever command you want, I always liked "hurry up"). We would repeat our command until they went pee, then they got a treat and a mini party (cheers, petting, lovin'...just like kids, make it a huge deal!). We just kept doing that until the time span was further apart and now they stand at the door to let me know they want out. I have a friend who trained their dog to ring a bell when they had to go out. I also think a crate is a great training tool, they normally wouldn't like to go where they sleep and/or eat.
Best of luck!
C.
PS. You should look into finding a good dog training and get the kids involved, there's a lot of responsibility in owning a pit bull with all those stereo types out there.