AKA, "How do I use decks only with my own students?"
To use create and use decks with only your students... (i.e., not for sale in the store)
Create your deck as usual and then, instead of "publishing to store", use the "private publish" button.
This indicates that your deck is complete and ready for use. It will then show up in your Library and be available for you to assign it to your students.
Private decks are not available in the store or for discovery by other users.
Private publishing is also useful for content you want to include in a "bundle" in the store, but do not want the item to be discoverable as an individual item.