Help with username

[Braelyn]

Alrighty, I have been looking high and low trying to figure out how I change my user name into my character's name. I found the account linking thing and thought that might work but it didn't work for me. Mehhh what do i do?!
Ps. I filled out my portfolio, but I'm not too sure if it's good enough. Can somebody look it over and let me know?