The mailinglist is open for registered users. You can sign up over here, or browse the archives to enjoy the friendly atmosphere before you subscribe.
This mailing list is not for general TeX/LaTeX help. Although there are probably very knowledgeable TeX and LaTeX users on the list, this is not the place to ask basic questions, and these questions will be silently ignored. The links page has references to help solve your problems in this case. Questions that do involve TeX and one of the tools, are of course welcome.
Also note that although the primary focus is on developers, other users are invited to join the list. We’ll need feedback on user interface issues, ideas for new programs and help for non-programming tasks, such as writing manuals, translating the user interface, and testing.