ASP.Net UpdatePanel ContentTemplate Render Question

Hello all,

I am writing a server control and I have pretty much everything needed except one thing I am stuck on.  In the rendercontents I am rendering out all the HTML tags and controls I need.  However, the controls okay easy to render with rendercontrol.   The question I have is how do I get into the inside of the update panel contenttemplate to start the HTML writes within those tags.  For example:

<asp:UpdatePanel runat="server" id="UpdatePanel" updatemode="Conditional">
  <ContentTemplate>
                <asp:Label runat="server" id="DateTimeLabel1" />
                <asp:Button runat="server" id="UpdateButton1" onclick="UpdateButton_Click" text="Update" />          
<table><tr><td></td></tr></table>    
            </ContentTemplate>
         </asp:UpdatePanel>

so for example in my render:
  protected override void RenderContents(HtmlTextWriter output)
        {
this.UpdatePanel1.RenderControl(output);
output.RenderBeginTag(HtmlTextWriterTag.Table);
}

I am stuck on how do I get into the internal part of the UpdatePanel.  Thanks all