Open your GUDHOST account, go to Websites and choose your site. The Admin link opens your WordPress login page, and your username is shown there too.
Your first password is shown once in your account when the site is ready. We never send passwords by email. Once you confirm you have saved it, it is removed from your account.
If you no longer have the password, reset it on the same page: choose the administrator under Reset an administrator's password and press Reset password, and the new password is shown once. You can also use Lost your password? on the WordPress login page, which emails a reset link to your administrator account.