The whole idea of the buddy stick is to allow the trainer to get in front of the dog a lot faster. If you make it properly there will be very little distance between the end of the pvc stick and the snap on the collar, around 2-3". You should start of by just walking your dog around the yard with the stick, it will be awkward and clumsy and they must get used to this. They will run into the end of it trying to run backwards and drag you around the yard, but this is also a good way to, teach your dog to stay out in front, as well as to quarter. Once the dog is comfortable on the stick you can start giving him the whoa command when he is running in front, or to the side of you; stop him with the stick by letting him run into it with his chest of by pulling backwards with the stick like a lead. As soon as you have him stopped you want to position the stick in such a way that it is directly below his chin with pressure against his chest, and no slack in the chain. If he tries to come towards you push him back into position with the stick (this is the advantage over a traditional lead). Do not allow him to take a step without correction, if the dog rebels by flipping and jumping just let him do it and stand him back up when he's done. As soon as the dog pauses for a few seconds without movement and seems to of accepted the command Lay the stick on the ground (it will be hanging from the dog's collar), walk up to him and stroke him telling him "good boy". You want him to associate standing in the place you stopped him as comfortable and everywhere else uncomfortable. Once he has obeyed for a few seconds tap him on the head and say "alright", do this a few times each session with each command lasting progressively longer. But remember to take your time and be fair and thorough, you are laying the ground work for the rest of the training. Be sure to allow the dog freedom and too run, allowing him to enjoy, and look forward to his yard-work.
The Whoa Stick is also good if a dog develops bad habits like sitting on the whoa command or ducking their head. If they sit simply pull them towards you and stand them up again, this forces them to stand up or be drug on the ground. They will eventually get the idea that if they stay standing they won't get drug across the ground. You do not have to be forceful in the dragging, just pull them towards you hard enough to shift the weigh off their hind legs, making them stand, or be drug.
If you've slipped up and been too rough with a young dog they will begin to duck their head when given certain commands (ones you've consistently been to rough with them on). If this happens with whoa, stop the dog like you have been doing, with the stick ending up below his chin. When the dog goes to duck his head in timidness (probably when you go to approach him) give him a little pop under the chin until he picks his head up. As soon as his head picks up, lay the stick down, approach him and praise him. If when you approach him he cowers again, pick the stick up and give him another little pop. Repeat this until you are able to approach the dog with him keepings his head high. The goal here is not to simply get his head up, but to get the dog to relax and feel comfortable under your command again. Once you have solved this problem, do not make the same mistake again!
Hope this helps guys, the whoa stick has its place and applications. But I still believe the simpler the better.