Building in Influence will allow you take different types of actions. From extractors, that allow you to mine your asteroids, to bioreactors where you will grow food. Each building is important to the Adalian colony and so is the placement of the building. In the testnet client we will not require you to source the materials needed to build these buildings, and instead you can simply construct warehouses and extractors during phase three.
More Information on buildings can be found here: https://wiki.influenceth.io/gameplay/exploitation/Buildings
Within testnet phase 3 the only requirements will be:
There are three steps to building infrastructure.
A. Find a lot that you want to construct a building at. B. Once the lot is selected in the bottom right click "Plan Building Site" C. Hit the "Select" button and select the building type you'd like to construct. D. Click "Place Site"