You can mine different resources in the dark colored provinces only. There are four types of resources in total: Oil, Gold, Cobalt and Uranium. You can select a resource in each of the four available provinces, but only if you occupied them first.
Via the trade button on the left of the menu you are able to manage your production, transportation, upgrade and the sale of your resources.
On the left above the goods icon you can navigate to the different types of resources easily.