After you log in for the first time, you will be presented with a screen that looks like the following, known as your "City Overview" page. The primary purpose of this screen is to alert you of anything that has happened to your city since your last login (such as other cities attacking you or stealing from you, your hero completing a quest, or your villagers finding abandoned resources).

You however don't need to worry about being attacked or spied on for the first couple of days after you sign up, since every city is invulnerable for the first three or so days after it is created (a period of time known as The Guard - the exact amount of time that you are protected for depends on the god that your city worships). Use this initial time period to become acquainted with the game, build up your city's forces and prepare yourself for battle.