1.when i click the save ,save successfull message has to be come like this green Colour message box
2.when i click save if some Error have Error message also dispaly like this Red Colour MEssage box 
   hi i want to display the Error message like this Please tell me if you know this i tried so many ways but  i can show Error alert only please  help me for this i have given my code also please help me  
    [HttpPost]
        public ActionResult Index(MailModel objModelMail, HttpPostedFileBase fileUploader)
        {
            if (ModelState.IsValid)
            {
                Thread email = new Thread(delegate()
                {
                    using (MailMessage mail = new MailMessage(from, objModelMail.To))
                    {
                        mail.Subject = objModelMail.Subject;
                        mail.Body = objModelMail.Body;
                        if (fileUploader != null)
                        {
                            string fileName = Path.GetFileName(fileUploader.FileName);
                            mail.Attachments.Add(new Attachment(fileUploader.InputStream, fileName));
                        }
                        mail.IsBodyHtml = false;
                        SmtpClient smtp = new SmtpClient();
                        smtp.Host = "smtp.gmail.com";
                        smtp.EnableSsl = true;
                        NetworkCredential networkCredential = new NetworkCredential(from, "XXXXXXX");
                        smtp.UseDefaultCredentials = true;
                        smtp.Credentials = networkCredential;
                        smtp.Timeout = int.MaxValue;
                        smtp.Port = 587;
                        smtp.Send(mail);
                        ViewBag.Message = "Sent";
                    }
                });
                email.IsBackground = true;
                email.Start();
                ParsingTemplate();
                return View("Index", objModelMail);//I need that successful message here itself
            }
            else
            {
                return View();//i need that Error Message here itself
            }
        }