1public HttpWebRequest CreatePostRequest(string data, string url)
2{
3    // Setup the request

4    var bytes = Encoding.UTF8.GetBytes(data);
5    var request = (HttpWebRequest)WebRequest.Create(url);
6    request.Method = "POST";
7    request.ContentType = "application/x-www-form-urlencoded";
8    request.ContentLength = bytes.Length;
9
10    // Write the data into the request stream

11    var requestStream = request.GetRequestStream();
12    requestStream.Write(bytes, 0, bytes.Length);
13    requestStream.Close();
14
15    return request;
16}

var request = CreatePostRequest("value1=aaa&value2=bbb&value3=ccc", "http://mysite.com/directory/form");