title: How to add reference to assembly in vs2012
body: <p>I need help on how to correctly add assembly in C# code.</p>
  
  <p>I start a blank project and trying to run the simple code below. but has referencing  errors.
  I know by default system.dll is included under the references folder.</p>
  
  <p>so why is it still complain that "'System.Configuration is not been referenced"? 
  Am I missing some manual steps? If so how do I do it?</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Text;
  using System.Threading.Tasks;
  using System.Net.Configuration;
  
  namespace ConsoleApplication2
  {
      class Program
      {
          static void Main(string[] args)
          {
              HttpWebRequestElement ae = new HttpWebRequestElement();
              ae.UseUnsafeHeaderParsing = false;
          }
      }
  }
  </code></pre>
  
  <p><strong>The type 'System.Configuration.ConfigurationElement' is defined in an assembly that is not referenced. 
  You must add a reference to assembly 'System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.</strong></p>
  
  <p>Thanks for helping</p>