How can I get my dog to walk next to me without pulling on the leash?

Keep your dog on a short leash with your left hand 10" above his head and your right hand holding the handle end of the leash. Walk him right into the door of an obedience class and get him to sit while the instructor starts teaching obedience training. You might think I am being a wise cracker but you can't expect your dog to obey you for just this one behavior. You need to learn how to control him in all aspects and then he will trust you and see you as his alpha, you lead and he will follow. If you can't go to an obedience class then start walking him and each time he steps one step in front of you give a sharp correction by snapping to the side on the leash, say NO in a firm voice. Every time you start walking and he stays with his head next to your knee praise and treat him with a quality treat not made in China. When giving a correction a quick snap sideways is need, no pulling back or up, snap to the side only.