There is also a channel for CC's free software development work: #creativecommons-dev.
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:
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!! email@example.com
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.