You can find the list of the note categories at the bottom of the NotesHolder main window, it looks like this:
Hint: Categories of Notes are not available in NotesHolder Lite. [More info about NotesHolder Standard]
To create a new Note Category click the (New) tab and enter a short name for the new category into the dialog box. Another way to create a new category is to right-click an empty space and select "create new category" in the menu. The second item of the menu allows for hiding the tab (new):
To delete or rename a category right-click it and choose the desired action in the menu.
Important! If you delete a category, you lose all the notes that belong to it.