Is there any reason to think he was abused, or are you just going off of the fact that he doesn't walk on the leash? Dogs don't come automatically leash-trained, and until he figures out what that leash is for he's likely to either a) not move at all (which sounds like what he's been doing) or b) fight against it. Try using a treat to entice him to take a few steps while on the leash and praise him profusely for stepping forward. As he gets used to the leash he'll figure out that it isn't going to hurt him, it's not tying him in one place, and he gets to go all sorts of fun places if he'll walk with it. As soon as he learns that he can walk with the leash, then work on getting him to pay attention to you and where you're going, again using treats and praise to urge him along, so that he learns that the most important thing during a walk is to stay beside you with a loose leash. If he acts shy or afraid, make sure the praise is encouraging but not overly effusive as that may scare him even more.