Quickest and easiest way to get going is find you local club racing ...Do some of there Track schools ( track Days ) and talk to them on what you need to get going .... obviously getting a car built to the rules of the class you want to run is just the beginning ...But you can get started with your street car at track days and get some track time ..... I run with one of the local track day schools here where I live .. Cascade Sports Car club or Team Continental , which are both sanctioned through ICSCC ... All depends on your area and who is running .... SCCA is at just about every track in the country , but most have local club racing that is a bunch less hassle to start racing with ... Then you can get into SCCA or NASA or ??