Have you signed up for an OB class yet? Almost all basic OB classes teach you first hand to walk on a loose leash. Otherwise there are hundreds or articles if you google.
The premise is almost always the same, but each person has a slightly different technique. You may want to google and see more than one to choose what you want to try, rather than just taking everyone at their word.
Also know that a lot of dogs don't walk nicely on a leash or can't be taught easily to until they have mentally matured more. Only at 20 months did we finally succeed, after many a class, extra help from trainers, and finally giving up for some months and not forcing it.
Hopefully the puppies are very young so we can deal with it early. The cool thing about pulling on lead is the dog actually thinks he has to pull to get from point A to point B.
Because at some point, he pulled you around on lead, and he can feel the tension of course on the lead, and associated that with getting to his desired location. So how can we fix this? Well for one stop walking forward when there is tension on the lead. If the puppy pulls, you must freeze (stop walking) After a bit the puppy will stop, maybe turn around and look at you, or even will walk up to you. This is when the lead comes loose and we can praise the puppy for walking with us and we can proceed walking. If the lead becomes tense again we again will freeze. After, well not getting very far on your walks for a few days, hes going to start getting the idea that walking beside you gets treats, happy voice and smiles, pulling gets you no where. Expect this to take some time, work on it daily /Good Luck : )
I agree with Sue; I have tried the method of stopping as soon as the dog tries to pull forward and inevitably the dog stops and turns around looking perplexed and then I step forward with my left leg and say "heel." As soon as the dog starts to pull you stop immediately and so forth and you will find that this will work quite successfully, it has worked with my dogs and some of them were quite stubborn to begin with, lol.