Here is a basic example of how to use the classes in Org.BouncyCastle.Tsp to send a TSP request to a server and collect the response.

TimeStampRequestGenerator reqGen = new TimeStampRequestGenerator();

// Dummy request
TimeStampRequest request = reqGen.Generate(
    TspAlgorithms.Sha1, new byte[20], BigInteger.ValueOf(100));

byte[] reqData = request.GetEncoded();

HttpWebRequest httpReq = (HttpWebRequest) WebRequest.Create("");
httpReq.Method = "POST";
httpReq.ContentType = "application/timestamp-query";
httpReq.ContentLength = reqData.Length;

// Write the request content
Stream reqStream = httpReq.GetRequestStream();
reqStream.Write(reqData, 0, reqData.Length);

HttpWebResponse httpResp = (HttpWebResponse) httpReq.GetResponse();

// Read the response
Stream respStream = new BufferedStream(httpResp.GetResponseStream());
TimeStampResponse response = new TimeStampResponse(respStream);