public ActionResult Index()
        {
            var model = new MyViewModel();

            // preselect items with values 2 and 4
            model.SelectedValues = new[] { 2, 4 };

            // the list of available values
            model.Values = new[]
            {
                new SelectListItem { Value = "1", Text = "item 1" },
                new SelectListItem { Value = "2", Text = "item 2" },
                new SelectListItem { Value = "3", Text = "item 3" },
                new SelectListItem { Value = "4", Text = "item 4" },
            };

            return View(model);
        }
 public ActionResult Index(MyViewModel model)
 {
     var selectedVal = model.SelectedValues;
     return View(model);
 }