To add a new Category to your Document Library, please take the following steps:
Click the Document Library icon from the CRM Homepage.
Click the Settings Cog in the right hand menu.
Make your way onto the Categories tab
Click the Add Document Category button.
Enter the name of your Category.
Click the Save button.
Your new Document Category is ready to go!
The next time you add a new document, you'll be able to select your new Category.