In page derivative, set trace to true : Page Directives « Page Lifecycle « ASP.NET Tutorial

<%@ Page Language="C#" Trace="true" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">

    void Page_Load()
    {
        Label1.Text = "java2s!";
        Calendar1.TodaysDate = DateTime.Now;
    }

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>Show Trace</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>

    <asp:Label
        id="Label1"
        Runat="server" />
    <asp:Calendar
        id="Calendar1"
        TodayDayStyle-BackColor="Yellow"
        Runat="server" />

    </div>
    </form>
</body>
</html>

5.2.Page Directives
	5.2.1.	ASP.NET Page Directives
	5.2.2.	In page derivative, set trace to true
	5.2.3.	Debugging ASP.NET Pages
	5.2.4.	Take advantage of page-level tracing
	5.2.5.	Setting a Culture Manually
	5.2.6.	Displaying a localized Calendar control.
	5.2.7.	Master page
	5.2.8.	EnableViewState='True'
	5.2.9.	Session State - Disabled
	5.2.10.	Session State - Readonly