Once you login to your account, you will see the Websites to protect area.
There's a text input called New Entry.
1) In order to add a domain, you must enter a valid domain name in the New Entry area. For example you can enter:
yourdomain.com
2) In order to add a sdomain, you must enter a valid domain name in the New Entry area. For example you can enter: subdomain.yourdomain.com