[support] OpenId authentication

Hi all, I need help understanding the OpenId moodle, what I need is to have a button that perform the authentication with Google, the idea is that users only will use Google's OpenId (https://www.google.com/accounts/o8/id) to enter my site, so, I want to optimize the User Log In Block and just place a Button or a link to perform the authentication with Google's OpenId. Any help is appreciated. Best Regards Gracias --- David