<asp:updatepanel runat="server" id="UP1" >
<content tempalte="">
<asp:fileuplaoad runat="server">
</content>
<trigger>
<asynchronouspostbacktrigger contolid="Event to submit or update buttons or as per ur need">
</asynchronouspostbacktrigger></trigger>
</asp:fileuplaoad></asp:updatepanel>