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.