Your population in Empires and Allies is what allows you to build more Industry buildings such as Lumber Mills and Ore Mines. The early buildings are easy to unlock because you generally will get that population just by completing goals - so you shouldn't have problems building farms and lumber mills. However, once you get to the Oil Well or the Ore Mine, you might find that you don't have enough population to build it. So how do you get more population?
The secret is to build homes. We will teach you how to build homes in Empires and Allies.
Houses are available to build under the Housing tab. Each house requires a bit of coin and some lumber in order to build. If you mouse over the home you can read additional information about each one. For example, the Small Cottage will cost you 60 lumber and 600 coins to build, however it will give you +40 population and 160 additional coins every 4 hours. Building these cottages will increase your population and allow you to build additional buildings and complete goals.
Be careful to only build the amount of houses that you actually need at any given time. It can be easy to overload your empire with houses and not have enough room for the buildings you actually will need. Expansions are expensive!
Hopefully this guide has taught you how to get more population in Empires and Allies!