When you signed up for Stargate, you selected a unique Account ID and Password to access your new account. When running the setup MyStargate installation, you may have been asked for this information to automatically configure your account on your computer.
The Account ID should be entered in the format username@stargate.net in lowercase letters. The Password should also be typed in lowercase letters. Both the Account ID and the username may be letters, numbers, or a combination of the two but they cannot have spaces or any special characters.