Open the Booking Sheet by selecting from the Sheet Type and Procedure Type then click the Edit Booknig Sheet Sheet button.
Once the Booking Sheet has opened you will see all its Categories, at the bottom of each column there is a New Category input box, Enter the name of the new category and click the Save Booking Sheet button to add the category to the bottom of that Column.
Once the Category has been saved you can drag it into position, click the Save Booking Sheet button again if you do move it. | 
