Whenever you attack an enemy or are attacked the battle panel is displayed. The battle panel presents you with several options for resolving the upcoming battle - fighting on the battlefield or seascape, resolving the battle automatically via a comparison of each force's statistics and withdrawing from the fight.
Next to the list detailing your forces and agents is one showing all the provinces under your control, their food production levels, public order and wealth, and can be sorted by each of those headings. It also shows those provinces adjacent to your own, so you can make informed decisions regarding future conquests.
When you have completed every action you want to during a turn, press the end turn button to advance to the next one. Before it is your turn again the AI-controlled factions will take theirs. This may mean you are attacked and must fight before you can consolidate or move your forces again.