First of all, the pug that is to be trained should always have a collar and leash on for all its lessons.
Give the Sit command while pushing down (gently) on the pug puppies hindquarters. When the puppy does sit, praise and pet it to associate this command with a positive experience.
In general it doesn’t take long for a pug to learn this very command, especially if treats are beeing used as a “thank you” after the puppy obeyed the command.
The meaning of the Stay command is to have your pug remain in one position until you release it. It can be very uselful in situation like standing on a cross street, having to wait for the traffic light to turn green. You tell your pug puppy to sit and stay. This way you won’t have the trouble of pulling your puppy back from the street, because it decided not to wait for the green light.
Once your pug has understood the sit command, you can put your hand on the puppies chest and exert slight backward pressure to keep your pug in position.
You should allow your pug to get up from the sit position only when you decide he can do so.
But do not test the puppies patience to the limits, since the attention span of a young dog (same as with young children) is very short.
Once you decide that your puppy can get up, call its name and say OK, and praise it lavishly and give it a tasty treat. After this is accomplished, we can move on to the stay command.
Make your pug sit and move a step or two back.
If the puppy attempts to get up and follow you, say firmly: “Stay!”, while raising your hand, the palm towards your pug, and command him again to “Stay!”
Every attempt to get up must be corrected at once. Return your pug puppy to the sit position and repeat “Stay!”. You can slowly increase the distance you step back, once your puppy begins to understand what you want it to do.
As a release command I would suggest you use “OK”. Walk back to your sitting and staying pug and say: “OK” as a signal that the stay command is over. Later, when your pug becomes more relieable in this respect, you can call it to you by its name, without walking back to where your puppy sits.