Add gridview column in code behind

I am working on gridview in C# and I need t开发者_运维问答o add a column dynamically. I need to achieve the following mark up in the code behind,

   <headertemplate>                          
    <a href="javascript:var popup = window.open('Pop.aspx? param=myParameter','Pop','width=200,height=200');">
     <asp:Label ID="Label1" runat="server" Text="ColumnName" 
      ToolTip="Click here for more information"></asp:Label>
       </a>
   </headertemplate>
<Itemtemplate>
....

The column has underline where user can click to open a popup.

Thanks.