Checking time taken for caaling url using proxy server\proxyscript

Hi All,
i m develpoing a .net Window application which has
4 texboxes(tbxURLmfor URL in URL Frame,tbxAddress for address in Proxy
server frame,tbxPort for port in proxy server frame,tbxProxyScript for proxy
script in proxy script frame) and a test button..The requirment is given below

STEP BY STEP GUIDE
1. Input the URL you want to test
2. Choose Proxy script/Proxy server with Address and Port Information/No proxy
3. Enter url to proxy script or info for proxy server in respective text box
4. Press test-button

---------------My Code is -------------------------------------------------
DateTime dt1 = DateTime.Now;
System.Net.HttpWebRequest myReq =
(HttpWebRequest)WebRequest.Create(tbxURL.Text.ToString());
//GetResponse for this request.
HttpWebResponse response = (HttpWebResponse)myReq.GetResponse();
DateTime dt2 = DateTime.Now;
lblTimeTaken.Text = Convert.ToString(dt2.Subtract(dt1));
--------------------------------------------------------------------
in this code , i m unable to set the value of proxy script textbox ,if any
or proxy server(Address and port) ,only thing which i do threough this code
is sending the url without any proxyscript ans proxy server(address and port
info) Can anybody tell me how can i do this thorugh the code....
...
i m working on window application as i need *.exe file rather than install
file ....


Thanks,
Deepak