All buildings are constructed by selecting a category and then a building using the main toolbar. For example, to build a forester lodge you would first select the button for Resource Production and then the button for a forester lodge.
After selecting the building, you can place it on the landscape. By default, you can rotate the building using the R and T keys. The green arrows on the building point to the front of the building, and show where the building may overlap a road. If a building cannot be placed, the green highlight will turn red.