create a web page as 2 parts
<script type="text/javascript">
$('#buttonid').click(function() {
    $('#divid').append("<form><input />etc etc etc</form>");
});
</script>

<asp:ScriptManager ID="sm" runat="server"></asp:ScriptManager>
        <asp:UpdatePanel id="upnl" runat="server" ChildrenAsTriggers="true">
            <ContentTemplate>
                <asp:Panel ID="pnl1" runat="server">
                    <!--personal info-->
                    <asp:Button ID="btn1" runat="server" Text="this button could validate personal info, hide pnl1 and show pnl2" />
                </asp:Panel>
                <asp:Panel ID="pn2" runat="server" Visible="false">
                    <!--address info-->
                    <asp:Button id="btn2" runat="server" Text="this button could validate address information and finally submit the form." />
                </asp:Panel>
            </ContentTemplate>
        </asp:UpdatePanel>