title: add image in treeView
body: <pre><code>TreeNode desktop = new TreeNode();
  desktop.Text = "Desktop";
  desktop.Tag = "Desktop";
  Mycomputer.ImageIndex = 1;
  Mycomputer.SelectedImageIndex = 1;
  desktop.Nodes.Add("");
  treeView1.Nodes.Add(desktop);
  
  TreeNode Mycomputer = new TreeNode("My Computer");
  Mycomputer.ImageIndex = 1;
  Mycomputer.SelectedImageIndex = 1;
  treeView1.Nodes.Add(Mycomputer);
  </code></pre>
  
  <p>I am using the <code>ImageIndex</code> property but where is the image?</p>
  
  <p>How do I choose my image and from where?</p>