open browser from window application

I need to open a url from a window application when a user click a button. However the URL which is a login webpage, i need to pass username and password as well, to authenticate the user. How can i do this in window application? How can i pass the parameters?

The purpose of this is to make our online stuff secure, that is why i am using this approach. The online help is open in a URL when the user clicks the button. We dont want it to be available to other users but can only use through our application. Any help would be greatly appreciated.

URLs that accept parameters use a form like "http://www.somedomain.com?username=hello&password=world". Assuming that your page accepts parameters then just create a URL like that and pass it to Process.Start.

Is there a way i can post instead of passing as querystring. Also do you have any other suggestions on making online help secure without any username password authentication.

You can use HTTP authentication. If necessary, you can also encrypt that using SSL. Have a look at the HttpRequest class.