If you have registered your number in 2020 season, and you are willing to keep your Start number and Class, login in your profile and later click on "Keep my number" button and all data will be transferred and saved to 2021 season. This service will be available till December 31, 2020. On January 1, 2021 this service will be no longer available.
First you need to register your number in championship, and later you will be able to register your participation in individual races
Before you register to championship, take a look at the list of numbers that are already reserved. See racers