This is a four-year-old dog you've just adopted. He's bound to be traumatized. How would you feel? Things are going to take a little time. First, have you taken him to tha vet? Is he in good health? While you're at the vet's you can ask a lot of questions, and probably pick up some useful pamphlets. Next stop, the library and/or bookstore. I suggest a book called SUPERPUPPY, and get a couple of other basic puppy care books too. Read! You don't get him to bond with anybody at this point. You let him settle down, and adjust, and get used to the idea that he's not going to get kicked out of this home like whereever he was before you took him in. Also, ask questions of people in the rescue group from whom you adopted him. If anybody tells you something that doesn't seem like common sense, ask a couple more people until you start to get a consensus.
Shelties are sensitive, trainable, smart, and good-natured dogs. Yours has been through a lot of rough stuff. Be nice to him, and give him a chance to fit in--he will try his best. Read the books. Good luck.