I've added it the way the instruction says, I do have the link added there and when I click on it it brings me to google login then I click on an email, it then goes back to login page. Do I need to configure anything else? How does it get saved into session and how can I access the google related info such as photo and email?

Fixed! Please ignore this, I was trying to use Google Login and it turns out that I've missed the part where you need to enable Google+ API from google's developer console. It was giving an error that relates to not having permission in the Settings > Event logs.

Thanks