Answer:
This involves a lot of training. I would invest in a gentle leader this will help. Note when the dog usually lunges and put the gentle leader and leash on during those times. When the dog lunges, jerk back on the leash sharply and say "no" strictly and firmly. Continue to do so until the dog no longer lunges. If the dog doesn't lunge then award the dog with a treat or playing with it with its favorite toy. Continue to do this every time the dog lunges.