First off I want to say you don't need anything to start except a SA2010+ helmet. What I mean by that is that your bone stock car will do just fine when you are just starting to get on track. It is encouraged to start with a stock car. Make sure the car is safe of course, meaning the battery is tied down, Battery terminals have good a good connection, safety belts in working condition, that you aren't leaking any fluids, and that your brakes are in good shape. Basically if you have a maintained and safe street car, you have a car that can go on track safely. A You can go that one step above and replace your rubber brake lines with stainless steel lines, a higher compound brake pad. and change your brake fluid to one with a higher boiling point. Those things aren't required when you are starting out but will be needed if you realise you enjoy pushing your car on track and decide to attend more events.
There are three main organizations that I recommend to get started with. The first being GPS Track time. The event host Jimmy Yu focuses on the beginners having fun and being well informed on what tracking is all about. GPS tracktime events are single day events. That can be good for you in case you don't like it you don't have to spend an entire weekend doing something you don't want to do. GPS also has the most tracktime out of any event that I have attended. What that means is you will get more driving time for your money. and quality time with an instructing helping you reach whatever your goal might be.
If you have any questions feel free to email me on the contact page.