To install the add-on, first locate the addons folder within your Blender folder. In most cases, it is located at C:\Program Files\Blender Foundation\Blender\2.78\scripts\addons. If you're on Linux, your add-on folder might be located at ~/.config/blender/2.78/scripts/addons/, where 2.78 is the Blender version you are using.

To install HabitatB, extract the .zip archive into this folder so that the complete path of the add-on is similar to Blender/2.78/scripts/addons/io_scene_habitat.

Now start up Blender and open the user preferences (File -> User Preferences...). Click on the Add-ons tab and enter Habitat into the search bar on the left. Enable the add-on by clicking on the check box. (Note: If there is an error when activating the add-on, please report the error message). User Preferences with Add-on

Tip: Now, click on Save User Settings at the bottom of the User Preferences window to keep HabitatB enabled when you restart Blender.