The first question would be if you have any experience in torrenting in general and private trackers in particular?
Some trackers are notorious hard to join or even completely closed, however others have open signups or application signups. You are also missing some German private trackers in your list.
Some German private trackers like the already mentioned World-of-Tomorrow or SpeedTorrent Reloaded or The Shinning allow application signup, if you are already experienced in trackers. For other trackers like Immortuous one can signup on their forums and apply for an invitation. Just visit their sites and look for an application/signup link.
Your question is too generic to provide more helpful answers.