You can create categories and terms by going to the series details page and clicking on the Reference materials tab.
* You can get to your series' page by going to your Dashboard > Works > Novels > Series and then selecting the novel title or cover.
You can set up to 100 terms per series.
You can set up to 20 categories per series.
You won't be able to create reference materials for series made by other users.
■How to create a category
1. Open the series details page and the reference materials tab for the work you want to add a category to.
2. Click "Create category".
3. Once you've entered a title for that category, click "Save".
4. Your category has been created.
Please check to make sure that the category you made is displayed in the reference materials tab.
■ How to create a term
1. Open the series details page and the reference materials tab for the work you want to add a term to.
2. Click the category you want to add a term to. You'll need to make a new category if there isn't one already there. 
3. Click "Create term".
4. Add the title and description of the term you're adding, then click "Save".
5. Your term has been created. Please check to make sure that the term you made is displayed in the reference materials tab.