In the Visual Studio There is option of creating Web Custom Control.
Here i m giving one very basic example which is msdn.
using System;using System.Web.UI;using System.Web.UI.WebControls;
namespace CustomControls{ public class FirstControl : Control { private String message = "Hello"; public virtual String Message { get { return message; } set { message = value; } } protected override void Render( HtmlTextWriter writer) { writer.Write(" " + this.Message + "" + "The time on the server is " + System.DateTime.Now.ToLongTimeString() + ""); } }}