[SerializableAttribute()] 
public class OrderFieldValue 

[Subscribe(Dynamicweb.Notifications.eCommerce.Order.Steps.Completed)]
public class OrderCompleteNotificationSubscriber : NotificationSubscriber
{
    public override void OnNotify(string notification, object[] args)
    {
        bool sendNewsletter = false;
        string emailAddress = "";
 
        Dynamicweb.eCommerce.Orders.Order MyOrder = (Dynamicweb.eCommerce.Orders.Order)args[0];
        OrderFieldValueCollection ofvCol = MyOrder.OrderFieldValues;
        foreach (OrderFieldValue orderField in ofvCol)
        {
            if (orderField.OrderField.SystemName.ToLower()  == "newsletteremail")
            {
               emailAddress = orderField.Value.ToString();
               sendNewsletter = true;
               break;
            }
        }
 
        if (sendNewsletter)
        { 
           SendEmail( emailAddress, "Order is completed" );    
        }
 
    }
}

class MyPage : System.Web.UI.Page
{
   public void CustomOrderFields(Order order)
   {
       FieldTypeCollection fieldTypes = FieldType.getFieldTypes();
       foreach (OrderFieldValue ofv in order.OrderFieldValues)
       {
           FieldType ft = fieldTypes.GetFieldType(ofv.OrderField.TypeID);

           string reqValue = Base.ChkString(Base.Request(ofv.OrderField.SystemName));
           switch (ft.DWName.ToLower())
           {
               case "text":
               case "largetext":
               case "integer":
               case "double":
                   ofv.Value = Base.ChkString(Base.Request(ofv.OrderField.SystemName, false));
                   break;
               case "checkbox":
                   ofv.Value = !string.IsNullOrEmpty(reqValue);
                   break;
               case "date":
               case "datetime":
                   ofv.Value = Dates.ParseAsDate(ofv.OrderField.SystemName);
                   break;
               case "link":
                   ofv.Value = reqValue;
                   break;
               case "filemanager":
                   ofv.Value = reqValue;
                   break;
               default:
                   break;
           }
       }
   }
}