How to send information from asp.net page to workflow and back?

using(WorkflowRuntime workflowRuntime = new WorkflowRuntime())
            {
                AutoResetEvent waitHandle = new AutoResetEvent(false);
                workflowRuntime.WorkflowCompleted += delegate(object sender, WorkflowCompletedEventArgs e) {waitHandle.Set();};
                workflowRuntime.WorkflowTerminated += delegate(object sender, WorkflowTerminatedEventArgs e)
                {
                    Console.WriteLine(e.Exception.Message);
                    waitHandle.Set();
                };

                ExternalDataExchangeService ExDateExchService = new ExternalDataExchangeService();
                workflowRuntime.AddService(ExDateExchService);

                POService poServiceInstance = new POService();
                ExDateExchService.AddService(poServiceInstance);

                WorkflowInstance instance = workflowRuntime.CreateWorkflow(typeof(FirstWFStateMachine.POWorkflow));
                instance.Start();

                
                PO newPO = new PO();
                Console.WriteLine("Please Enter Item Code to be sent Purchase Order of");
                string ItemCode = Console.ReadLine();
                Console.WriteLine("Please Enter Due Delivery Date of Purchase Order of");
                DateTime DueDeliveryDate = Convert.ToDateTime(Console.ReadLine());
                newPO.ItemCode = ItemCode;
                newPO.PODueDeliveryDate = DueDeliveryDate;

                poServiceInstance.CreatePO(instance.InstanceId, newPO);
                Console.WriteLine("New PO created for item: " + newPO.ItemCode + " with Due Delivery Date: " + newPO.PODueDeliveryDate.Date);
                
                

                Console.WriteLine("Do you want to approve Purchase Order");
                while ( (Console.ReadLine().ToLower()) != "y")
                {
                    Console.WriteLine("Current status of Purchase Order : Created");
                    Console.WriteLine("Waiting to be Authorised");
                    DumpStateMachine(workflowRuntime, instance.InstanceId);
                    Console.WriteLine("Do you want to approve Purchase Order");
                }
                poServiceInstance.AuthorisePO(instance.InstanceId, newPO);

                Console.WriteLine("Do you want to send Purchase Order");
                while ((Console.ReadLine().ToLower()) != "y")
                {
                    Console.WriteLine("Current status of Purchase Order : Created");
                    Console.WriteLine("Waiting to be Sent");
                    DumpStateMachine(workflowRuntime, instance.InstanceId);
                    Console.WriteLine("Do you want to send Purchase Order");
                }
                poServiceInstance.SendPO(instance.InstanceId, newPO);
                DumpStateMachine(workflowRuntime, instance.InstanceId);

                System.Console.ReadKey();
                waitHandle.WaitOne();

            }