Editing Categories
Select Edit from the Categories menu:

and the following window appears listing the current categories (the numbers in parenthesis are the associated hourly rates).

Add. Click on Add to add categories.  A window appears where you enter the category and associated hourly rate.  The category name is limited to 27 characters (see figure below).

Edit. Click on a category in the list and click on Edit to edit the category (or double-click on the category).  A window appears where you edit the category name and associated hourly rate.  The category name is limited 27 characters (see figure below).

Delete. Click on Delete to delete the selected category.

Sort. Click on Sort to sort the categories alphabetically.

To keep your changes, click on Done.  To cancel your changes, click on Cancel.