Thanks very much for replying!!

Yes ,We cann't post data to anthor form ,I do post data to anothor page:
"<form action="responsepage.aspx" method="post" >

 <asp:textbox id="textbox1" runat="server"/>

</form>"

Just as what is shown above,the code dosn't work.
The problem is even the code in the book Beginning ASP.NET using C# don't work here.

How to solve the problem?