You can change your username through the Settings section of the site, available from the top of the website when you click where your name is shown. Select 'Change' alongside the 'Username' line.
You can choose a new username that is between 5-16 characters long. You can use alphanumerical characters, or a hyphen.
What will change
A username change will update your name throughout the entire site where the old name was referenced. The change will not hide your previous activity on the site. Changing your username will not hide your identity on the site, it will update your old name to the new name.
There is an admin fee in place for all account type changes so you will need to have your payment method to hand to complete the process.
When will the change take effect
Username changes are processed immediately. You may be required to log out and back in.