How do I secure a username for my fan page?

You first need to get a minimum of 25 fans. Then go to
http://chatbooth/username to register a unique username (vanity URL) for your fan Page. See this Help section on Facebook for more assistance with usernames.

If the username you want shows as not available (and when you go to pull up the URL, nothing comes up), you’ll need to contact Facebook directly. See this directory of forms. I have not yet found a form specifically for this request, but you could try a form like the one for intellectual property infringement.