// Get all current Controls in the collection.
for (int i = 0; i < pagesSection.Controls.Count; i++)
{
  Console.WriteLine("Control {0}:", i);
  Console.WriteLine("  TagPrefix = '{0}' ",
      pagesSection.Controls[i].TagPrefix);
  Console.WriteLine("  TagName = '{0}' ",
      pagesSection.Controls[i].TagName);
  Console.WriteLine("  Source = '{0}' ",
      pagesSection.Controls[i].Source);
  Console.WriteLine("  Namespace = '{0}' ",
      pagesSection.Controls[i].Namespace);
  Console.WriteLine("  Assembly = '{0}' ",
      pagesSection.Controls[i].Assembly);
}

// Create a new TagPrefixInfo object.
System.Web.Configuration.TagPrefixInfo tagPrefixInfo =
    new System.Web.Configuration.TagPrefixInfo("MyCtrl", "MyNameSpace", "MyAssembly", "MyControl", "MyControl.ascx");

// Execute the Add Method.
pagesSection.Controls.Add(tagPrefixInfo);

// Add a TagPrefixInfo object using a constructor.
pagesSection.Controls.Add(
    new System.Web.Configuration.TagPrefixInfo(
    "MyCtrl", "MyNameSpace", "MyAssembly", "MyControl",
    "MyControl.ascx"));