City Interface:
Here is where you upgrade your city and recruit troops. Other functions such as the armory, city hall (taxes etc) and research can be accessed through the links on the left and bottom of the screen
World Interface: Access regions and plantations from this screen.
Farm Interface: Here you can capture farms. Farms produce grain every 10 minutes for 4 hours (default, extended through alliance upgrades).
Chat box: This is where you can talk in specific channels to other players. World chat costs 2 gold per message, please be wary of that.