IRC
For those not familar with IRC have a look at the Wikipedia definition and download a software program for your operating-system so you can participate in the CC channel.
There is a Creative Commons IRC channel on the freenode network, called #creativecommons.
There is also a channel for CC's free software development work: #creativecommons-dev.
IRC help
Nicknames on IRC are on a per-server basis. We use the freenode server exclusively, so registering a nickname is a one-time deal.
First change your nickname to something unique:
/nick mattl
Then, when you have chosen your nickname register it with the nickname service.
/msg nickserv register password email
Replacing password with a strong password and email with your email address. For example:
/msg nickserv register sci3nce!! punkish@creativecommons.biz
You should save this password in your IRC client, if you can. On IRCCloud, click the name of the network (freenode) on the right of the screen, then click edit and expand the advanced options to find a place to save your nickserv password.