When you’re using HttpWebRequest and POST method, you have to set a content (or a body if you prefer) via the RequestStream. But, according to your code, using authRequest.Method = “GET” should be enough.
In case you’re wondering about POST format, here’s what you have to do :
ASCIIEncoding encoder = new ASCIIEncoding();
byte[] data = encoder.GetBytes(serializedObject); // a json object, or xml, whatever...
HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
request.Method = "POST";
request.ContentType = "application/json";
request.ContentLength = data.Length;
request.Expect = "application/json";
request.GetRequestStream().Write(data, 0, data.Length);
HttpWebResponse response = request.GetResponse() as HttpWebResponse;