How do you replace the rear brake light on a new VW beetle?

It is actually very easy. Open your trunk. You will see a cap on the inside part of the rear light. It has a wing-nut that you need to turn counterclockwise and remove. That releases the tension on the outside plastic cover. Now with tender patience you will pull out the entire rear cover from the outside. It has retention spring around the outside cap that you may have to gingerly pry on with a flat-head screw driver. Be careful not to chip the body paint. Once you have removed the light fixture you will see a bulb housing that you turn a quarter turn that will allow you to replace the old bulb.

Replace everything in reverse order.