C# C# Streams and Data Processing Streaming Data on the Net WebClient

What does the question want me to do

why this code note note working

Program.cs
using System;
using System.IO;
using System.Net;

namespace Treehouse.CodeChallenges
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(GetTreehouseHome());
        }

        public static string GetTreehouseHome()
        {
            string treehouse = "";
            // Put code here
            using(var webClient = new WebClient())
            {
                byte[] treehouseBytes = webClient.DownloadData("https://www.teamtreehouse.com");
                using(var stream = new MemoryStream(treehouseBytes))
                {
                    using(var reader = new StreamReader(stream))
                    {
                    }
                }

            }

            return treehouse.ReadToEnd();
        }
    }
}