Did you see this video?
YouTube - Free Shaping with an Australian CattleDog | AskDrYin.com
Most people use a clicker, but Dr Yin just says 'yes' as a marker for 'that right there was perfect'. A clicker is more precise, but also requires very good timing from you!
Your dog is going to learn by trail-and-error what it is you want from him. Break down the idea you have in mind in small steps and reward them, upping the criteria as the dog progresses. So the dog touches the box - good. He then touches the box with his paw - good. Nose touches now no longer 'work' - right, dog understands that the paw touch is the way forward. He'll try more in that direction now.
Basically you are the treat machine, and the dog is going to learn how to activate you - and you keep moving the 'button', the behaviour that works, toward the goal you have in mind.
Edit to add: an extremely educational thing to do (which I keep intending to do but can't find someone nuts enough to do it with) is to play a shaping game with another person - take a goal behaviour in mind and without any verbal or gesture communication, only the click, let them figure out by trail-and-error what you want. Then reverse the game so you're the one being trained. I saw a video on this a while ago and can't find it now, sadly.