Click on the System > List of Values menu to launch the List of Values Page.
Select the Employee Categories from the left panel
Select the Employee Category entry under Employee Categories from the left panel. The list of available categories are displayed.
Select the required category type from the Category Type drop down for which you wanted to add new category.
Click on the button to add a new record.
Type in the description of the category.
Click on Apply button to save the values.
For More Information check http://wiki.greytip.in/wiki/Add%20New%20Category#section-Add+New+Category-HowDoIAddANewCategory