To begin adding doors and windows, select either the Doors or the Windows button on the Building Tab toolbar. The property panel (the left panel) will display a catalog of available doors or windows and some properties that can be set.
To place a door or window, select the desired door or window from the catalog. Once selected, place the mouse cursor over a desired location on a wall and left-click to add the door or window. The same door or window can be placed multiple times in different locations.
Note: Doors and windows must be placed on a currently existing wall.
Properties: Various properties of doors and windows can be set before placing them.