start by letting him drag the leash loose around the house. After a while, pick it up and start with little tugs to follow you and treats when he does. After he walks well in the house, then go outside where there are distractions. The finer points of leash training are better left to those who are better at training than I. Everybody has their own preferences and have dogs that respond to different techniques when it comes to getting them to walk nicely.