using System;

using System.Net;

using System.Net.Http;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        CookieContainer cookieContainer = new CookieContainer();

                HttpClientHandler handler = new HttpClientHandler { CookieContainer = cookieContainer };

                handler.CookieContainer.Add(new Uri(@"https://www.google.com"), new Cookie("test", null));

        string referer=null;

        using (HttpClient client = new HttpClient(handler) { BaseAddress = new Uri(@"https://www.google.com") })

                {

                    client.DefaultRequestHeaders.Add("Referer", referer??"");

    }

    }

}