Become his world. Hand feed him his meals, and then after a while start teaching him new "tricks/obedience" commands for his food. GSDs love to learn and that will help create a bond with you. Most GSDs will bark at strange people. Work on bonding in your house first. I would avoid large crowds until he really knows you are his person. And maybe get even further away from the crowds. Find his "safe zone" first, then just do the sitting and calming. Get his mind on you.Go to Leerburg.com and read and watch all the free info on pack structure (even though it is just you and him) and introducing a new dog to your house.
dogbyte Cathy, Rossi ( the Dutch shepherd) and Gunny (the Czech/DDR GSD) with Zoey, Chance,Xara,Gracie, and Jaden snuggled deep within my heart