The OpenSees Community

Wait do you mean you want to edit the wiki articles for OpenSees on wikis such as:
https://en.wikipedia.org/wiki/OpenSees
https://www.everipedia.com/opensees-uc-berkeley/

Or you want to specifically edit internal hosted wiki here?
http://opensees.berkeley.edu/wiki/index.php/Main_Page

Because both of the first two sites have their own separate registration process, I think registration for the internal wiki is locked IIRC at least at the moment. Hope that helps.