Stories that have combination locks will generally provide some way to discover the combination. That might require piecing together multiple clues to get the various numbers in the combination. Once you have the combination, you dial it like a regular combination lock.

The dial itself can be dragged to dial it (in the game, at least, the above is just a screenshot), and the buttons can be used to turn it left or right one tick mark, for fine adjustments. Just like a regular combination lock, as soon as you change direction you lock in the number you were at.

Clicking Start Over resets the lock to 0 and clears the combination, in case you mess up. At any point you can try to open the lock using the combination that's shown. What happens if you try the wrong combination depends on the story!