Whenever a civilian is selected you will see a white flashing outline around him, and his picture will be shown in the toolbar. 

In the toolbar you see a picture of the selected civilian along with information about him. On the map you see your civilian units, a variety of terrain, towns, and defensive military encampments (small tents). 

There are nine types of terrain that always supply a resource: fertile hills(wool), plantations(cotton), open range(livestock), farms(grain), orchards(fruit), hardwood forest(timber), dry plains(grain), ranches(horses), and scrub forests(timber). The last three types cannot be improved to produce more than one unit per turn.

There are two types of terrain that might conceal mineral resources: barren hills(coal or iron), and mountains (coal, iron, gold, gems).

Some of the other types of terrain on the map become valuable later in the game, like deserts and tundra.