Hi Mallorie,
The xml file where you can define Categories and sub-categories is located in your web_resources directory within the “categories” folder. The file, named tree.xml is blank by default, but here is a link to a short guide and video on how to set this up:
http://help.percussion.com/how-to/how…
Also, here is sample file with some categories and sub-categories already defined to get you started:
http://help.percussion.com/Assets/Hel…
You can click the last link he pasted and copy the source or you can right click on the link and select “Save Target As”