You may enter any text that you like (up to 50 characters) to jog your memory in case you forget your password. If you need your hint, it can be displayed on the Account Login page by entering the email address used when your account was created and then clicking the Display your password hint link

DO NOT enter your password directly as the hint as this information may be displayed to anyone who enters your email address. Instead use some cryptic phrase that will act as a reminder for you without allowing anyone else to guess the associated password.