title: System.Net.Http: missing from namespace? (using .net 4.5)
body: <p>TL; DR: I'm new to this language and have no idea what I'm doing</p>
  
  <p>here is my class so far:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Net.Http;
  using System.Web;
  using System.Net;
  using System.IO;
  
  public class MyClass
      {
          private const string URL = "https://sub.domain.com/objects.json?api_key=123";
          private const string data = @"{""object"":{""name"":""Title""}}";
  
          public static void CreateObject()
          {
              HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
              request.Method = "POST";
              request.ContentType = "application/json";
              request.ContentLength = data.Length;
              StreamWriter requestWriter = new StreamWriter(request.GetRequestStream(), System.Text.Encoding.ASCII);
              requestWriter.Write(data);
              requestWriter.Close();
  
              try
              {
                  // get the response
                  WebResponse webResponse = request.GetResponse();
                  Stream webStream = webResponse.GetResponseStream();
                  StreamReader responseReader = new StreamReader(webStream);
                  string response = responseReader.ReadToEnd();
                  responseReader.Close();
              }
              catch (WebException we)
              {
                  string webExceptionMessage = we.Message;
              }
              catch (Exception ex)
              {
                  // no need to do anything special here....
              }
          }
  
          static void Main(string[] args)
          {
              MyClass.CreateObject();
          }
  }
  </code></pre>
  
  <p>when I do csc filename.cs, I get the following error:</p>
  
  <blockquote>
    <p>The type or namespace name 'Http' does not exist in the namespace 'System.Net' (are you missing an assembly reference?)</p>
  </blockquote>