The purpose of the Service Categories table is to group certain types of services into categories for reporting purposes (see screen shot above for commonly used Service Categories). Although you will need to put some thought into the Service Categories you use from the start, new categories can be created if a need arises, those categories can be added to existing Services (to be discussed in the following section), which will be reflected on any new reports run.
Click New from the Service Categories table to add a category or double-click on an existing entry to edit.