title: How to POST request using RestSharp
body: <p>I m trying to POST the request using RestSharp client as follows 
  I m passing the Auth Code to following function </p>
  
  <pre><code>public void ExchangeCodeForToken(string code)
  {
      if (string.IsNullOrEmpty(code))
      {
          OnAuthenticationFailed();
      }
      else
      {           
          var request = new RestRequest(this.TokenEndPoint, Method.POST);
          request.AddParameter("code", code);
          request.AddParameter("client_id", this.ClientId);
          request.AddParameter("client_secret", this.Secret);
          request.AddParameter("redirect_uri", "urn:ietf:wg:oauth:2.0:oob");
          request.AddParameter("grant_type", "authorization_code");
          request.AddHeader("content-type", "application/x-www-form-urlencoded");
  
          client.ExecuteAsync&lt;AuthResult&gt;(request, GetAccessToken);
      }
  }
  
  void GetAccessToken(IRestResponse&lt;AuthResult&gt; response)
  {
      if (response == null || response.StatusCode != HttpStatusCode.OK
                           || response.Data == null 
                           || string.IsNullOrEmpty(response.Data.access_token))
      {
          OnAuthenticationFailed();
      }
      else
      {
          Debug.Assert(response.Data != null);
          AuthResult = response.Data;
          OnAuthenticated();
      }
  }
  </code></pre>
  
  <p>But i am getting response.StatusCode = Bad Request. Can anyone help me for how do i POST the request using Restsharp client.</p>