Better get that dog trained to walk nicely on a leash. He needs exercise badly or you'll continue to have more problems. I have a Doberman, a Lab and two Chihuahuas. That Doberman would have killed those Chihuahuas with his exuberance to play if he hadn't been tired out a few times a day. I suggest a puppy class so you can get some training tips, socialization for your dog and for you. It's fun. Get a reputable trainer though.
If you browse through these threads, there should be some good info about teaching your dog not to pull....how you stand still and hold fast when he makes tension in the leash and resume walking when he gives you slack.....or turn and walk the other way. I like to make random turns all over the place, dog sitting when I stop, which I do frequently. It makes the dog pay attention to you better...he's wondering what's coming next. Then you use lots and lots of praise and treats when he does well. That's a start, but do put some time and effort into your dog. You'll be glad you did.