If the race is open for pre entries you can enter the event once you have been notified by mail. To get this notification often you must have raced previous years but organizers may also offer this option for other reason to some participants.
If you have raced the year before and know they offer pre entry slots former participant and you want this options, we suggest you contact the organizers to make sure you dont miss out. You find their contact details on the right hand side of the online entry form or their own website. to