Le mercredi 11 avril 2018 08:34:23 UTC+2, Senna Van den Bosch a écritÂ*:
Op dinsdag 10 april 2018 20:42:42 UTC+2 schreef Dave Nadler:
On Tuesday, April 10, 2018 at 2:23:03 PM UTC-4, Senna Van den Bosch wrote:
I have bought my first glider and picking it up saturday.
It's registered in Germany but doesn't have a competition number,
how are they chosen? Where can you register one?

In what country???

Belgium, in Europe.

Congratulations to your first glider!
As for competition numbers - most people put on what they like. You probably can register it with your national aeroclub (useful if somebody else shows up with the same competition number at a central contest), but that's up to you.