How to show watermark text from global resource files in asp.net

using System.Threading;
using System.Globalization;
using System.Resources;

ResourceManager rm;
protected void Page_Load(object sender, EventArgs e)
   {

      initResourceManager();
      TextBoxWatermarkExtender.WatermarkText=  rm.GetString("ResourceName");

  }
private void initResourceManager()
  {
     Thread.CurrentThread.CurrentCulture = new CultureInfo(Session["Language"].ToString());// provided you have a Session["Language"] with Language value like "en-EN" or "de-DE"
     Thread.CurrentThread.CurrentUICulture =                                                                                             Thread.CurrentThread.CurrentCulture;
     rm = (ResourceManager)Application["RM"];
  }

using System.Threading;
using System.Globalization;
protected void Application_Start(object sender, EventArgs e)
 {

    Thread.CurrentThread.CurrentCulture = new CultureInfo("en-EN");
    Thread.CurrentThread.CurrentUICulture = Thread.CurrentThread.CurrentCulture;
    Application["RM"] = Resources.ResLanguage.ResourceManager;

 }