An activity is a note that a user posts to their Google+ stream. The activity methods allow you to insert a new activity to a stream, list a collection of activities or get detailed information on a specific activity.
To use these Choreos:
You'll need a Google account. If you don't already have one, you can sign up here.
Open a new web browser, navigate to the authorization URL returned by the InitializeOAuth Choreo, and click "Accept" to grant the app access to your Google account.
Run the Google > OAuth > FinalizeOAuth Choreo, specifying the callback ID returned earlier by the InitializeOAuth Choreo. This process will return a Refresh Token which can be used along with the Client ID and Client Secret to authenticate with Google.
This short video demonstrates how to use our OAuth Choreos, and it's a good idea to take a break and watch it now before you dive into this step.