If you get to any screen that requires your username or password and you can't remember either one or both, use the link that says "Forgot your password?".
In the space provided, enter your email address. Be sure to enter the email address that was used when you registered. Otherwise the system will not be able to figure out who you are.
Click on the button that says "Request UserName/Password Now" and your username and password will be emailed to you instantly.