Twillio outbound call with two-way communication

Question

I'm developing a basic call using .ASP.NET feature where the requirement is when I click a button, it will trigger a call to another person. The call is two-way, which I can communicate with my clients for example.

I am using Twilio to do this..

This is my code :

 public void OutboundCall(string toPhoneNumber, string fromPhoneNumber)
        {
            var call = CallResource.Create(
                twiml: new Twilio.Types.Twiml(
                    "<Response><Say voice=\"Polly.Amy\">I am  a good programmer</Say>\r\n <Play>https://demo.twilio.com/docs/classic.mp3</Play>\r\n</Response>"
                ),
                to: new PhoneNumber(toPhoneNumber),
                from: new PhoneNumber(fromPhoneNumber)
            );
            Console.WriteLine(call.Sid);
        }

It seems like when I call the number, it can only display the predefined message.

My question is, how can I have a two way communication with my clients just like a normal phone call?