post method for edit in MVC using Automapper

public ActionResult Edit(int id, User userDetails)//
        {
            try
            {
               var dbContext = new MyDBDataContext();
                Mapper.CreateMap<learningmvc.user,>();             
                var user = Mapper.Map<learningmvc.user,learningmvc.models.user>(userDetails);               
                  dbContext.SubmitChanges();
                  return RedirectToAction("Index");
                  
            }
            catch
            {
                return View();
            }
            
        }