Basics
Resources
To construct buildings or recruit units you need resources. You receive resources automatically from your resources production (timber camp, clay pit, iron mine). You also receive those resources when you are not logged into your account.
The amount of resources that you get depends on the level of your resource buildings. It is important to build up your warehouse to make sure that you don't lose the resources that don't fit. At the top right of your screen you can see how many resources you currently have. The progress bar shows you, when the storage is full.
The numbers show the resource amounts that are stored right now. (601 wood, 538 clay, 716 iron). The max. amount of resources in this example is 1000, so that's why the progress bars are approximately in the middle.
Hint: Always try to spend all your resources in buildings or units. If you're getting attacked and there's nothing to plunder, it's likely that the enemy will lose interest in your village.
Population
Buildings and units also need population. In contrary to the other resources, population is not produced over time but provided by the farm. The higher its level the more villagers can be supplied.
The number shows the amount of villagers that additionally can be supplied. So for example 821 Spearmen could be recruited in this village. The progress bar shows the ratio between free and used population, in this case a very small amount of population is already used, and there is a lot of free population.
First steps
In the beginning you mostly need one thing: Resources. The timber camp cuts wood, the clay pit collects clay and the iron mine produces iron. The more you expand those buildings the more they produce. When you first join a world it is recommended to build up your resource production by a few levels.
After you have secured a good base production of resources you can start building troops. In the barracks you can start recruiting spear fighters. Spear fighters offer some protection against would-be attackers who might want to plunder your resources. They are not usually good offensive troops, but they are useful for raiding very small, undefended villages in order to plunder their resources.
In addition to recruiting troops, there are also other ways to help protect your village and defend your resources in the early stages of the game. One way to protect your resources is to research technologies like the attic, cellar or bunker in the warehouse. Another good deterrent is to build a wall (Level 4 headquarter needed). The higher your wall level the stronger your village's basic defense will be. This means your enemies will suffer higher losses when they attack villages with higher wall levels.
If you find you have excess resources, you might want to consider building a market. (Level 8 headquarters needed). In the marketplace, you can see what your neighbors are offering and trade away resources you don't want. You can also create your own offers.
You should also look around your area to find a good tribe to join. It is always easier to fight and defend in a group. It is also a good way to meet some nice people!