- The plain password is fine if you are making a request to the https page not the http one.

- Use a cookie container that is attached to every request you make

- Request the login page before you post to it (in order to get the cookies it sets on visit) using GET

- Use the same cookie container you used in the GET and post the user/pass but encode it in ascii first.

- Take the & off of the first argument aka &txtusername= should be just txtusername=

- You may need to spoof the browser because they do not want automated requests.