By the import of courses we mean the possibility to include courses from other departments in your own section of the schedule of classes. It is a prerequesite that the department offering the course has released the course for import.
If you want to import the course of another department into your branch of the schedule of classes, please click on the Import of lectures menu item. Search for the desired course and click on the Edit button.
Under the Assign foreign lectures to own headers tab, select the desired heading of your department and click on Submit. You can remove imported courses in the same way.
If you want to release courses of your department for import by others, set the Import of lectures field to permit import (see also How do I create a new course?).