you can add one here is the syntax
this one goes on top of Defauklt.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Default3" %>
and this one is the code Default.aspx.cs
public partial class Default3 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
your code here...
}
}