public void SetBasicAuthHeader(WebRequest request, String userName, String userPassword)

{

    string authInfo = userName + ":" + userPassword;

    authInfo = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));

    request.Headers["Authorization"] = "Basic " + authInfo;

}

public void FetchTasks(string url, string accessToken)

{

    var httpWebRequest = HttpWebRequest.CreateHttp(url);

    request.Headers.Add("Authorization", "Bearer "+accessToken);

    httpWebRequest.BeginGetResponse(new AsyncCallback(FinishedWebRequest), httpWebRequest);

}