1. Follow instructions on Drush install instructs on Drupal – https://www.drupal.org/node/594744
  2. Download and install Composer – wizard – https://getcomposer.org/doc/00-intro.md#installation-windows
  3. Download and install Cygwin – wizard – https://cygwin.com/install.html
  4. Downlaod and install Git – https://git-scm.com/download/win
  5. Download and install Drush for Windows – http://docs.drush.org/en/master/install-alternative/#windows