Its pretty easy to subscribe to the forum.
1- You must be a registered user on the AAVSO site. You don't have to be a member, but you have to be registered.
2- Near the bottom of the pages with messages in the forum is a link from the word "subscribe". Click on it.
3- Three choices will appear:
That's it!
Mike
Links:
[1] http://www.aavso.org/forums/variable-stars/cataclysmic-variables-cvs