If it's a DKU championship you want to sign up to, then you can fill out a formula by following this link.
At some championships you have to be a member of DKU to participate (e.g. the Danish Championship).
DKU championships are always played in Denmark.
If it's German Open you want to sign up to, then contact Hotel prinz-Luitpold-Bad.
This championship is always played at 2. Saturday in Juli at Hotel Prinz-Luitpold-Bad in Algäer Alpen, Germany.
You can also check out this German site: www.krolf.de