Place your cursor over Reference Data and left click on the sub-option Incident Size Classes.
Left click on the Add button 
located at the bottom left hand side of the table.
Enter the new incident size class by completing the displayed fields.
Use your Tab key on your computer keyboard to navigate through the fields or left click on each individual field.
Left click on the Insert button 
to save the new information.
Left click on the Cancel button 
if you do not wish to save.