The flight needs to be supervised by an official observer.

This person certifies that the Colibri and you did indeed make the
flight in the same sailplane. The OO is responsible for ensuring that
all the requirements for the claimed flight were made.

If you didn't follow these steps, then you can still be proud of the
accomplishment, and you have a personal record of this flight. But in
order for the flight to be officialy recognized, all the rules must be
followed. Unfortunately, as in most beaurocracies, it's the paperwork
that counts, while the actual performance is just a small detail in the
process.

-Tom