You can change your username on the Account page of your settings, here.
Here's how to get to this page:
Go to your Settings. It's in drop down menu on the right side of the page.
Go to your Account page. It's in the side bar to the left.
Click "Change Username" to enter a new one.
Your new username will immediately take effect and you can start logging in with your new username.
Filed under: Accounts
Need more help? email us at firstname.lastname@example.org