The NC is a moderated community, so only members of the forum can join. This is in place to prevent people who have been banned from NC joining the community. If you would like to be a member, you should click the "join community" button, and then either post on Jazzy's journal (dandelion) saying who you are at the forums and that you want to join the_nc, or PM at the forums telling me what your LJ username is. If you want to be added fast, I suggest posting a comment as those go straight to my inbox and I'll likely get the message faster. :)
As of 6/3/05, all non-member and anonymous posts are being screened- this is to prevent spam by certain banned users. If you don't want your post screened, I suggest you join the community- anyone who has not been banned from NC itself will be added to the community, so don't worry about not being considered an "active" user or anything like that.