Here is information to register with VHSL for 2019-20. VHSL's registration system is at: whistle.vhsl.org. Once there click on "registration" and then on "officials". Follow the instructions. If you officiate more than one sport, you can register for all of your sports at once. You are supposed to be able to select more than one referee association per sport (CSOA/RSRA/ASOA).
This web site is also where you will watch the rules clinic and take the required VHSL officials' test.