HttpWebRequest request = (HttpWebRequest)WebRequest.Create("
http://www.site.com/login.php");
request.Method = "POST";
string data = "username=myname&password=mypass&login=Go";
byte[] byteData = Encoding.UTF8.GetBytes(data);
request.ContentLength = byteData.Length;
Stream stream = request.GetRequestStream();
stream.Write(byteData, 0, byteData.Length);
string response = new StreamReader(request.GetResponse().GetResponseStream()).ReadToEnd();
}
}