title: C# Web API - Authenticating with OAuth on subsequent calls
body: <p>Ok, I am working with Google APIs and they use OAuth2. I need to have multiple API calls of my own that do different things with the Classroom API. All of the examples I have seen for C# make the user authenticate THEN they use the google service.</p>
  
  <p>I need to authenticate one time and send that access token to the API for additional calls.</p>
  
  <p>My end goal is something like this:</p>
  
  <ul>
  <li>User logs in with google.. they give back the access  token and such</li>
  <li>Pass that token in an authorization header</li>
  <li>API takes that and pulls out the credentials and passes them to the google service (<strong>THIS</strong> is where I am stuck)</li>
  </ul>
  
  <p>I can get the access token pretty easily using Postman, or with my own web app. </p>
  
  <p>When I send that over in the Authorization header (Postman sends it as bearer) I don't know what to do with it from there.</p>
  
  <p>Do I parse it? Is there something in the .Net Google API library that makes this easy? </p>
  
  <p>Seems like this should be a common scenario, but I can't find any tutorials or guides on this.</p>
  
  <p>Thanks!</p>