Custom Controls ASP.Net Tutorial

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebControlLibrary1
{
    [DefaultProperty("Text")]
    [ToolboxData("<{0}:WebCustomControl2 runat=server>")]
    public class WebCustomControl2 : CompositeControl
    {
        protected TextBox textbox = new TextBox();
        protected override void CreateChildControls()
        {
            this.Controls.Add(textbox);
        }
    }
}