You do not directly control the actions of your units, in fact you can't tell them what to do at all. Rather, each unit type has certain predispositions. For example Rangers are predisposed to explore unexplored areas on the map. Rogues try to find and accumulate money. Warriors like killing monsters.
Wizards like to research new spells.
And so on. Buildings also support your economy and heroes in various ways. Each costs gold to construct. Markets generate gold that is gathered by tax collectors and brought to the castle. Heroes find gold that you can tax, caravans from outposts bring in money as well.