These courses are intended for USSF training, but most of the material applies very well to both USSF and high school games. There are differences between them. Look in your NFHS rule book for a table that lists the differences between the leagues. Also, please note that the online classes are only part of the training requirement.
Review the rules in any order, and take the quiz following each section (on the Florida website, anyway) to see how well you're understanding the material. The Florida website link has been added to the navigation sidebar on this site so you can go back to it, anytime, at your convenience.
The USSOCCER Referees Resource Center has a lot of GREAT downloadable videos and training materials including "Offside Made Easy", "The Gray Areas", and "Myths of the Game". You will need the QuickTime movie player to watch the videos. You can get that at
Take a look, and have fun!