It's always kind of connected to your personal page, in that you can always switch back and forth by clicking "use page as..." under "Account" in the upper right hand corner.
Also, the only way your "Likes" count on someone's page is if you're using your account as your profile/your self, not as your page.
What I do is stay logged on as my profile/myself, and go and "Like" anybody on these threads that asks. Then I post on their wall that I'm saying "hello" or whatever, then type @PetDesign. Any page name you type after "@" shows up as clickable.
See my example on "bookgeekery" I just did it there :)
Hope this helps everyone♥
-KaylaB
Then, when you have at least 25 "Likes" you go to
http://www.facebook.com/username/ ..........and you can select a new username that doesn't have all those numbers after it.