Update: the "White Hand" guild now has its own personal forums over at http://www.whitehandguild.com - if you want to join, go to the "Recruitment" forums (found here), read the sticky here and make an application post.
If you just want to have a chat, the easiest way would probably to join the "ign" channel by typing:
It will then say something like "Joined Channel: [#. ign]", where # is some number usually between 1 and 5. You can then chat in that channel by prefixing anything you wish to say with /<number>. For example:
/5 Wazza !
There is another chat channel called (imaginatively enough) "ignchat" - you should be able to find someone idling in one or the other channels.
Enjoy Wow, please come again. ;)
edit: Updated post to reflect the new (as of a few months ago) way to join the guild. (Mekon)