If you have not used this service before you need to begin with creating an account by clicking on the "Create account" button that is below the login. That will take you to a form where you enter you details and confirm. The service will then send a confirmation email to the email address that you used. Once you have confirmed your email address you can login with that email and the password that you created.
Once you have logged into the service a good start is to click on the "information" link on the top left site of the submit page. There you will find instructions on how to use the validation service.