RallyCross is easy to do - all you need is a car which passes a basic safety inspection and if you don't own your own approved helmet, regions will often have "loaner" helmets available (convertibles must have factory hard tops in place) 

Once you have the safe car, use the "find an event" link above to find events near you. From there - use the links to find registration, directions and other information and then show up on site the day of the event. 

Once there you will want to empty your car out, check in (or register if there was no online registration) and go through tech inspection where officials will double-check your car to make sure it's ready. 

Next, there will be a "run/work" order. As RallyCross officials are also drivers. If it's your first time, don't worry - experienced people will be there to help guide you. Ask questions, make new friends!

When it's time for you to work, check in and work (usually this will be on course helping pick up cones which are knocked over, but it could be helping in the timing trailer, helping on grid or other duties. 

When your turn to make runs make sure to be ready for a parade lap prior to make competition runs. Someone in Grid will let you know when to head to the start line. Once at the start line make sure your windows are rolled up and have fun and avoid hitting cones when the starter notifies you to go.

The drivers on course while you're working are the people who will be working when you are on course - so give it your best effort to help everyone have a great event. 

Once the event is over, there is usually an awards ceremony, and it's likely that some of those new friends you made all head to dinner for post-event bench racing.