Sample Code working with UpDatePanel Dynamically.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class _Default : System.Web.UI.Page
{
    Label lblSample = new Label();
    protected void Page_Load(object sender, EventArgs e)
    {
        lblSample.ID = "lblSample";
        lblSample.Text = "Sample";
        this.form1.Controls.Add(lblSample);
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("<Table bgcolor='Green'>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("<Tr>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("<Td>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("<Font color='White'>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("<Strong>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(lblSample);
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("</Strong>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("</Font>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("</Td>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("</Tr>"));
        UpdatePanel1.ContentTemplateContainer.Controls.Add(new LiteralControl("</Table>"));
    }
    protected void Timer1_Tick(object sender, EventArgs e)
    {
        lblSample.Visible = !lblSample.Visible;
    }
    
}