How do I create or edit a Category?

Category management is under Manage Site. Access Mange Site from the three dots at the top right of the home page.
 

Categories

Click on New Category to create a new one. Use the pencil to edit the name of a current category. If a Category has not been used at all in Vidigami (for any year), you will also have the option to Delete it when you click on the pencil.