You mean you want to train him to respond when you say “Sit”?
assitant
Hmmm...  I’m not sure that’s possible with an inanimate object like a dog.  Dogs are animals, and they’re not really a good fit for learning.  The same goes for computers, cars, plants, and lots of other things.
assistant
How can I train my dog to sit?
user
What do you mean, train?
assistant
Teach him how to sit on command.
user