<input type="file" name="file" />

<input type="submit" value="Загрузить" />

[HttpPost]
        public ActionResult RestaurantImages(HttpPostedFileBase file)
        {
            if (file != null && file.ContentLength > 0)
            {
                   var fileName = Path.GetFileName(file.FileName);
                   var path = Path.Combine(Server.MapPath("~/Images"), fileName);
                   file.SaveAs(path);
            }
            return RedirectToAction("RestaurantImages");                          
        }