If you don't have a harness yet, I would not recommend walking him.. Using his collar alone could really hurt his little neck.
Once you have a harness on him and he is outside it will be easier. He may need some time to sniff around and get comfortable. Lots of bug scary things outside especially for a young puppy.
Once you and him are more comfortable just hanging out outside, you can sort of tug him when he's on his harness to get him going. Chances are, he's curious to see whats outside and around the block. Treats may help as well to get him to follow you.