title: Download a file from a WebForm using C#
body: <p>I need to download a file from a website (not written by me).
  I have a valid username/password to access it, and I can do it manually.
  But I want to create an automated procedure (in C#) to download it periodically.</p>
  
  <p>Manually I have to login, browse to the download page, select some combo box and then click "Download".
  This link performs a postback and returns the requested file.</p>
  
  <p>I think I should use WebClient.DownloadFile, but I can't figure out how to pass all the necessary data and request the postback the correct way.</p>