Username is not your name on Facebook. It creates a link to your Timeline. Example, if your username is victoria.13 the path to your homepage is http://facebook.com/victoria.13. Today, How Facebook will help you create a username.
First, login to Facebook:
Then, click here and go to General Account Settings :
Next, enter your new username into Username Box (here is marith.heith9). If Username is available
click choose Save Changes:
Done.