Task Name: Grain mill
Description: A grain mill increases the production of all your croplands. In order to be worth its price, you need to have a high enough base production.
How to do this task: In order to construct your grain mill you first need to meet the prerequisites of it. In this case that involves a level 5 cropland. Upgrade this to level 5 as you have upgraded all your other resource fields. Note how the cost of the upgrade increases with every level. This may take you a while to accomplish.
Once you have the level 5 cropland you can build your grain mill. Go to your village center and click on an empty building site. As you will see the grain mill is not in the infrastructure tab, as it upgrades your crop production you will need to click on the resources tab. Construct this building to receive your reward.
You can read more information on the importance and use of your grain mill here.
Reward: Grain mill increased from level 1 to level 2.