Folders may used in CMF to help organize content. Folders may contain any kind of content object, including subfolders.
To create a new Folder at a given place in the site heirarchy, navigate to the place where you want to add the new Folder, then click the "Folder Contents" link in the actions box. This will bring up the "desktop" view of the current Folder, listing the content objects and subfolders. In the desktop view, click the "New..." button.
You will now see the "Add Content" form. This form provides a list of the kinds of objects you can add at this location (based on the permissions you have), and descriptions of the available objects.
Select "Folder" from the listing, enter an id for the new folder in the "id" field located below the listing of available object, and click the "Add" button to add the new Folder.
After submitting the add form, you will be taken to the "desktop" view of the newly created Folder.