To use Google Authenticator as a two-factor authentication method, you must first pair with the user's Google Authenticator App, by displaying a QR code to them. This QR code is generated using a secret code that only you know. When the user logs in, they must enter the code displayed on their authenticator app, which you validate against the secret code used earlier.
You can use the web service to pair, or call "https://www.authenticatorApi.com/pair.aspx" with the following parameters:
You can use the web service to validate a pin, or call "https://www.authenticatorApi.com/Validate.aspx" with the following parameters: