To work the Club Excel and Travel games you must take the Entry Level course to become a certified USSF referee.All entry level referees are known as Grade 8's. (Note "Grade 8" is USSF terminology, it has nothing to do with what grade level your child is in school.)
Experience as a K-2 referee is helpful, but not required. Anyone can sign up and take the course.
As of 2009, the Entry Level Referee Clinics are conducted online. It is broken up into several modules with a short test at the end of each module. Once you complete all modules you then can sign up for the Field Training and Final Test session which are held on a Saturday from 9-3.
The on line course is primarily open from July to December each year. You would then be certified to referee that following year.
Grade 8 minimum age requirement- In order to take the Grade 8 course, you must be turning 13 years old by June 30th of the year that you will first start refereeing. In other words, if you are taking the class in July-December, you must be turning 13 by June 30th of the following year.