Create an application for example https://developers.google.com/google-apps/calendar/instantiate but the library from Google not have the right class. What to do where to look; usingSystem;usingSystem.Threading;usingSystem.Threading.Tasks;usingGoogle;usingGoogle.Apis.Auth.OAuth2;usingGoogle.Apis.Calendar.v3;usingGoogle.Apis.Calendar.v3.Data;usingGoogle.Apis.Services;namespaceCalendar.Sample{ classProgram { staticvoidMain(string[] args) { UserCredential credential =GoogleWebAuthorizationBroker.AuthorizeAsync( newClientSecrets { ClientId="CLIENT_ID_HERE", ClientSecret="CLIENT_SECRET_HERE", }, new[]{CalendarService.Scope.Calendar}, "user", CancellationToken.None).Result; // Create the service. var service =newCalendarService(newBaseClientService.Initializer() { HttpClientInitializer= credential, ApplicationName="Calendar API Sample", }); ... } }}