I wouldn’t hurt to join WKA and get your road race endorsement prior to going. At the same time, contact WKA and get the current 2018 Tech Manual and go over everything pertaining to the two classes Bob mentioned.
Make sure you have all the pre race safety tech items covered before you go. E.G. full width rear bumper, brake tether, every thing cotter pinned, safety wired, helmet Snell 2010 or newer, etc.