at http://twistedmatrix.com/trac I see no button like "new ticket" for adding this defekt. I can only browse the tickets :( Do I need to login?
Yes, that's right.
If yes how can I register?
What about the "Register" link, on the top right? :-)
Remember to add your login name to the Cc: field of the ticket you create (or any other one you are interested in): you'll receive email at each change.