How do I get a hiddenfield id name in default.aspx.cs?

Question

<asp:TemplateField HeaderText="Customer ID"> 

<ItemTemplate>     

    <asp:HiddenField runat="server" visible="true" ID ="HiddenField2"   Value='<%#Eval("Customer ID") %>'   >

</asp:HiddenField>     

        <asp:Label runat="server" ID="HiddenField1"  Text ='<%#Eval("Customer ID")%>' Visible="true" >

</asp:Label>

 </ItemTemplate>

 </asp:TemplateField>