Click on the mine entrance to gain money, then hire miners. To do good work, these miners have needs you need to take care of: supply them with beers and lantern, hire guards, blacksmiths and healers to keep good working conditions.
Beware, because all this must be kept balanced! For example, each miners wants to have at least 2 beer.

The game still needs to be a little more balanced, but I hope you'll enjoy it !