You can create folders as a place to store sets of courses. You can add your own folders or any other public folder to your folder set.
This is also a great way for you to share your groups of courses with other users.
Note - you cannot set folders to private. All folders are public by default and are visible to all users.
Courses within folders that are not public will be shown, but they are will not be accessible to users unless they are authorised - e.g. if it is passworded.