To Open Pop Window and Pass Value Using C# in .net

 String javaScript = "window.open('Message.aspx?ID=" + lblRefNum.Text + "', null, 'height=150,width=700,status=yes,toolbar=no,menubar=no,location=center, scrollbars=yes');";

                    ScriptManager.RegisterStartupScript(this, typeof(string), "OPEN_WINDOW", javaScript, true);