Instructions
Construct buildings that increase your population limit. Each time you create a unit, it is counted against your population limit, which is how many units you can have at any one time. Buildings --- such as farms or castles --- increase this limit, so you can build additional units.
Construct a wartime building. These buildings produce the simplest warring units the race has to offer and can typically be built from the beginning moments of the game. An example of this building type would be a barracks or stable.
Click on the building. The list of units it can spawn will be shown in portraits around the building.
Click the portrait of the unit you want to create. Once the construction timer elapses, the unit will spawn beside the building.