How to validate cookie in post request?

Question

I started with the following post to create my method: Stack Overflow Post

I created the following method:

    public HttpResponseMessage GetStuffFromRest(MyRequest myData)
    {
        var baseAddress = new Uri(_baseUri);
        var requestXML = CreateBody(myData);
        var response = new HttpResponseMessage();
        var cookieContainer = new CookieContainer();

        using (var handler = new HttpClientHandler() { CookieContainer = cookieContainer })
        using (HttpClient httpClient = new HttpClient(handler) { BaseAddress = baseAddress })
        {
            #region Trying Cookie Container                
            httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", "myUserName");
            var c = new Cookie("Cookie", HttpContext.Current.Server.UrlEncode(myData.Cookie));
            cookieContainer.Add(baseAddress, c);

            response = httpClient.PostAsync(_myMethodUri, new StringContent(requestXML, Encoding.UTF8, "application/xml")).Result;
            #endregion

        }

        return response;
    }

myData.Cookie is populated from another rest service that I called and obtained the cookie from.

When I call another web service I am getting a 401 status code back.

I believe it has to do with how I am passing the cookie to the rest service.

How can I verify what exactly my headers contain? (Particularly the cookie)

UPDATE: Rephrased the question.