Right-click the note to which you want to assign a category and click Categories.
The Categories dialog box opens, displaying a list of available categories. Mark the check box next to any categories you want to assign to the note.
You won't notice a difference in the note itself, but you can choose to display notes by category, as shown here. To do so, click By Category in the task pane.
If you use lots of notes, color-coding them may not be an effective way to keep them organized. Instead, you can assign each a category (such as personal or business). You can then easily view all notes by category, allowing you to keep your notes organized.