how to signup user using google-plus integradation in web?

Question

Hi I'm trying to integrate google plus in web application. I have added google-plus button using this link page as instructed.When i click on the button it will open window access to user to accept or cancel. But how do i use that object for user login to the application?

function signinCallback(authResult) {
if (authResult['status']['signed_in']) {
 // Update the app to reflect a signed in user
 // Hide the sign-in button now that the user is authorized, for example:
 document.getElementById('signinButton').setAttribute();
} else {
 // Update the app to reflect a signed out user
 // Possible error values:
 //   "user_signed_out" - User is signed-out
 //   "access_denied" - User denied access to your app
 //   "immediate_failed" - Could not automatically log in the user
 console.log('Sign-in state: ' + authResult['error']);
}
}