Thought categories can be managed here. To create new categories, use "Add New Category" form below. Below, you can also choose Title, Description and Icon.
To create 2nd-level categories and 3rd-level categories, choose respective 1st-level and 2nd-level category from "Parent Category" dropdown below. Choose this carefully as you will not be able to edit Parent Category later.
To reorder the categories, click on their names or row and drag them up or down.