Hi,
In Html page you can not use directly asp.net controls like
<asp:textbox xmlns:asp="#unknown" /> or <asp:button xmlns:asp="#unknown" />
tags.
so please try this code instead of
<asp:TextBox ID="Txtname" runat="server" Width="398"></asp:TextBox>
this to
<input type="text" name="Txtname" id="Txtname" />
and instead of
<asp:button id="Btn" runat="server" text="Send" xmlns:asp="#unknown" />
this to
<input type="button" name="Btn" value="Send" id="Btn" />