Uhm, dunno, really...
It seems to me that you've registered as "enigmas" which means you'll have to register again with a new nick if you want to change it. Problem is, you can't register more than once (using the same e-mail address), so you'll have to "unregister" first.
Drop me a note at email@example.com
if you need help with that.
After you've published a number of messages on the board, you'll be upgraded to a "senior member," by the way