You have to use the "nose magnet" to get him to go along. The nose magnet = delicious food. Try tidbits of boiled white meat chicken. Be really upbeat and lure the dog to go with you. Sounds like your dog has a lot of fears - puppy class is good for that so you might want to consider that.
Teddy
had similar leash issues. He'd sit down, eat grass, sell one spot for 10 minutes. I just taught him the "with me" command, used chicken, and within no time he was strutting along wagging his little tail loving his walks.
Good Luck!!