If you have more the 25 fans you can claim your short URL. Ideally, you
should try and get your first 25 fans quickly, in order to claim it as
soon as possible. You are be able to choose your Vanity URL at http://www.facebook.com/username just like a user selecting a username for their profile.
instead of the long version:
Why is this important?
If you have a vanity URL, you can provide your customers with simple
shortcut to your Facebook page. The easily-remembered URL helps to
strengthen your brand and improve traffic to your page, and then
hopefully, your website too!
Don’t worry! Any old links to your Facebook page will still work; it’s
just a shorter (and tidier) URL that is easier to advertise and easier
for your customers to remember.
Please take care when choosing your short URL as you can’t change it
after registration. Make it something that is clearly linked to your
business, and to your website. Check your spelling carefully; once
you’ve submitted it, you can’t change it!
For more details: