public void TestMethod1()
    {
        HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create("https://www.invoicera.com/app/api/xml/1.1/");
        request.Credentials = new NetworkCredential("MYKEY", "jj");
        request.Method = "POST";        // Post method
        request.ContentType = "text/xml";
        request.Accept = "application/xml";


        string xml = "<?xml version="1.0" encoding="utf-8"?><request method="getAccountInfo"></request>";

        byte[] bytes = Encoding.UTF8.GetBytes(xml);

        request.ContentLength = bytes.Length;

        using (Stream putStream = request.GetRequestStream())
        {
            putStream.Write(bytes, 0, bytes.Length);
        }

        using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
        using (StreamReader reader = new StreamReader(response.GetResponseStream()))
        {
            string resp = reader.ReadToEnd();
        }

    }