Please be aware that your username is the name that appears on your profile, and it can't be changed. Don't choose a nickname or something like 'SweetPea' or 'PussyGalore' because that is what the judges will look at when they have chosen the winning chapters, and they want to find out more about the person behind the story.
Be professional and show them you mean business! Our suggestion is that you use your name (first name and surname) or your pen name.