Board Thread:Support Requests - Designing Your Wiki/@comment-14947040-20130904195319/@comment-5175866-20130905180226

The Category Tree should be enabled on your wiki by default at Special:CategoryTree on your wiki. Sub-categories can be created by categoriziing a category page into a category. If there is no category page then simply create a page with the prefix Category: followed by the name of the category. After that edit it to the text you would like and use the category section to categorize the category page into, another category.

Hope this helps! If you need more help just reply here.