Martin has excellent advice. I would like to add, a few more quick tips. If your dog is pulling backwards it's afraid of the leash and where it may go. Take him off the leash and play with him outside for a moment w/the leash in your hands. Let him smell it and show him how it's not going to hurt him or you. Rub him with it, put in around your body and his and lots of fun! fun! fun! for the pup! the leash is fun! happy! When you click it on his collar, don't pull. Let it be "lax" for a moment and play some more! do hold it but no tension. Call and play so he can see the leash & the connection with you, but don't tug. Reward! fun! Then, slowly move next to him tap your leg and if need be SHORT little TUGS forward. NO dragging or forcing. I'm going to run out of room, but I hope this helps and good luck You both will do great! :)
When your dog pulls away when you are walking you should just hold the leash tight and short, this way you will minimize their movement. You should however get it trained to walk as well as yourself. Visit the www.cesarsway.com/tips/thebasics/problems-on-the-walk website for more information.