Basically what I am trying to say is that the journey that you have undertaken is a long one, a long long one. This is not a simple, quick game. By playing this game you will be committing yourself to days in front of the computer, be they rewarding or frustrating ones. You start with one group of settlers. Settlers can irrigate land, build roads and most importantly build cities.
Cities work on a very simple principle.
You start with a population of one, which requires one food icon to sustain it. Food is grown in the lands around your city. In your City View this is represented by grain. If your city produces two food icons the surplus goes into storage. The surplus adds up.