WeekendRef
Go to your local school and ask if they have any extra rule books. Also, the officials manual, casebook and simplified/illustrated if they have them. They should have one (coaches don't use them much,
) Or, go the NFHSA site and order them.
http://www.nfhs.org Or, your state High School Association. Or your local officials association.
Also, check with your local officials association as to how to join them and how to get registered with the state. They will be glad to help you.
At any level, you should have a basic knowledge of the rules. It saves wear and tear on your hide.
Then, next year, get registered! You'll feel more confident regardless of what level you do.