title: Update field from c# driver
body: <p>I have a document collection like this:</p>
  
  <pre><code>{
      "_id" : ObjectId("4fb21439f31dfd122ce39c4a"),
      "Name" : "Freelander 2",
      "Manufacture" : "Landrover"
  }
  </code></pre>
  
  <p>I am using the C# driver, and want to check whether the "Name" field exists; if it does not, I need to update it from the code.  Can someone help on this?  Please share sample code because I am a newbie to mongoDB.</p>