How to do update Delete method using CodeFirstApproach and ViewModel in MVC4?

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Hi I want to do update delete Process using Code First approach and view model in mvc4.I had create the view and i done insertion process using Code First approach and ViewModel because my DB is fully normalized and i used EF .
so I used code first approach and ViewModel. Now I complete the Insertion process . Now I want to know how to do Update and Delete process using Code First approach and ViewModel. Please any one give me the solution..


My Model

public class CustomerModel1
    {
        public System.Guid CustomerID { get; set; }
        public string DisplayName { get; set; }
        public string PrintName { get; set; }
 }

public partial class ContactModel
    {
        public System.Guid ContactID { get; set; }
        public string DisplayName { get; set; }
        public string PrintName { get; set; }
        public string Mobile1 { get; set; }
        public string Mobile2 { get; set; }
        public string Phone1 { get; set; }
        public string Phone2 { get; set; }
        public string Email1 { get; set; }
         public string Website1 { get; set; }
}

My VieModel

public class CustomerViewModel
{
  public System.Guid CustomerID { get; set; }
    public string CustomerName { get; set; }
    public System.Guid ContactID { get; set; }
    public string ContactPerson { get; set; }
    public string PhoneNo1 { get; set; }
    public string PhoneNo2 { get; set; }
    public string MobileNo1 { get; set; }
    public string MobileNo2 { get; set; }
    public string Website1 { get; set; }
 }
  public class VisitorsEntities1 : DbContext
{

 public DbSet Customer    { get; set; }
 public DbSet Contact { get; set; }
}

My Controller

public ActionResult Create()
    {
  return View();

    }

    [HttpPost]
 public ActionResult Create(CustomerViewModel viewmodel)

  {
     var Customerobj = new Customer()
        { 
         CustomerID= Guid .NewGuid (),
         DisplayName = viewmodel.CustomerName,
         PrintName = viewmodel .CustomerName
   };
    var Contactobj = new Contact()
        {
            ContactID= Guid.NewGuid(),
            DisplayName= viewmodel.CustomerName,
            PrintName=viewmodel.CustomerName,
            Mobile1=viewmodel.MobileNo1,
            Mobile2 = viewmodel.MobileNo2,
            Phone1= viewmodel.PhoneNo1,
            Phone2=viewmodel.PhoneNo2,
            Email1=viewmodel.Email1,
            Website1=viewmodel.Website1

            db.Customer.Add(Customerobj);
            db.Contact.Add(Contactobj);
            db.SaveChanges();
       return View();
   }

Here i complete the insert process using CodeFirstApproach and ViewModel. Insertion is working fine. Now I want to do Update ,Delete and Details (Index) Process . How to do that using code first approach and ViewModel.

Thanks...