Leashing a pup up for the first time is certainly a shock for them, since they're always used to being free. LOL, if somebody suddenly put a leash on me right now, I wouldn't flop around, but I'd turn rabid on them
I'd hold the leash myself, and not walk, just stand there until he stops flopping and calms down. Lesson over for the day. Repeat. Just a little bit at a time, walk a few feet, done. Etc. Try to always end the session on a positive note--dog calm and getting some sort of treat (you don't have to give him a whole hunk of meat, just something little). Has worked for me in the past. Tying the dog up for short periods makes sense, though I've never done that myself.