public static string XML_Post(string xmlData)
{
    string PostAddress = "https://api.google.com/xml";

    WebClient wUpload = new WebClient();
    HttpWebRequest request = WebRequest.Create(PostAddress) as HttpWebRequest;
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";
    Byte[] bPostArray = Encoding.UTF8.GetBytes(xmlData);
    Byte[] bResponse = wUpload.UploadData(PostAddress, "POST", bPostArray);
    Char[] sReturnChars = Encoding.UTF8.GetChars(bResponse);
    string sWebPage = new string(sReturnChars);
    return sWebPage;
}