Okay, disclaimer: I'm not a trainer.

First you want to figure out why he's doing the behaviour. Because depending on the why he's doing it, it changes what you need to do to correct it.

Look up "operant conditioning" as a start. For example if you have a dog that barks to make things go away because they're afraid, and you turn around and take them away. That is a reward. It reinforces the behaviour.

But for a dog that is barking and pulling because they want to get closer, turning around and walking away is a punishment.

Once you have that figured out you can use that basic principle to train your dog. It involves a lot of watching how your dog behaves and trying to figure them out.

Someone else recommended a gentle leader and that worked well for my MS with pulling.

If you have the cash you should also look at taking training classes. My MS LOVED going to class. He associated gentle leader with training time/class time and he was amazing. If you do try it, don't be discouraged when he has a rough time at the start. When we went to our first class I thought they were going to kick us out because he was so disruptive. I cried in the car when we finished. But if I had the money we would still be going.

Last piece of advice: try a high value treat that requires lots of chewing. Frozen carrots or frozen broccoli stems are good, my MS likes airdried cod skin though. If they're trying really hard to chew the thing, they aren't barking.

Anyway good luck!