Not sure about classes, but there are a few forums and places.
you might like:
http://www.thepoetryforum.co.uk/forum.php
(Geoff and myself participate there)
also
http://wildpoetryforum.com/phpBB3/index.php but they seem to be being picky about letting new members in (as Geoff will attest).
also you might check out the Poetry group at Goodreads:
http://www.goodreads.com/group/show/233._POETRY_
I could also recommend a few instructional poetry books if you like.