You're getting good advice, so I just want to add my "I feel your pain"...we adopted a dog who was given up b/c her previous owner didn't have time to train her and all that. And while I'm glad he finally realized this, his tactics of keeping her in her crate all the time backfired on him (and us). One of his complaints was that she could not get the whole potty thing. Turns out she had a bladder infection.
To get her on the right track once her infection was under control, we worked a schedule. After any naps, go outside. After eating, go outside. After play time, go outside. After being in the crate, go outside. And our other dog always went too. Confine her to her crate when we couldn't keep attention focused on her (over night, when we were out, etc.). She didn't really start getting it until we got her into obedience training. Same thing happened with our other dog - she never had an accident again after she went to obedience training.
The only problem with the dog now is that she can't go outside by herself. She lives with my mom now (long story involving our other dog), and she has to go out with my mom's older dog. And he's so slow getting to the door, that she just dances like crazy waiting for him. It's kinda cute actually, but it can be a bit of a pain, from what I hear.
Good luck with the new puppy!