A List can be saved in a folder of type Public or type Private. The folder structure is editable by a User. There are three types of folders are: public folders, mailing lists and private folders. Public folders are shared and accessible to all Users. Mailing list folders are used for mass mailings. Private folders are only accessible to a single User.
To Create a New People List Folder:
1.Highlight a List folder in which to create a sub-folder.
2.Click the Create New Folder icon 
located above the folder tree. The newly created folder will appear at the bottom of the sub-folder list. The new sub-folder is highlighted and the cursor is active inside the name of the new folder ready for the sub-folder name to be entered.
3.Type the name of the new sub-folder, then click elsewhere. The re-named subfolder appears.