Extract the file to the folder with the installed game. Trainer must work in parallel with it, because when you start the game, press [Alt] + [Tab]to go back to Windows, run the trainer, set what you need and using the same keys back to the game.
During the game you can use the key [+] (on the numeric keypad) to activate the codes.
Note: Trainer only works with version v1.03 games.