How do I set up a custom Facebook username?
Setting up a custom username (also called a vanity URL) for your Facebook page is easy! These are great if you plan to reference your Facebook page in an advertisement or on the radio.You need to have at least 25 fans before your page will be eligible for a username. The age of your page is also taken into account. It may be a while before Facebook will allow you to set a username. (This wait period was meant to insure that people could not run off with one another's brand names.)
While logged into Facebook, go to http://www.facebook.com/username/. You will see a drop-down list of available pages. Choose the one for which you want to set a username. If the page is eligible, you will see a text field where you can enter the username. DOUBLE CHECK WHAT YOU TYPE! Once set, a username cannot be changed.