Just save the file with extension .pgn and open it via a chess program.
Game download

The PGN is just a text file. You can save it and open it in any text editor or utility that reads PGNs (such as a chess programs).

Where is this 'Download button at?
In the Archive at the top and on a game under the navigation buttons. It is a down pointing arrow over an open box.
When I hit download for a game, I get question from Windows about what "app" I want to use for download. I am not sure how to download the file so that I can open it in "chess engine" web site. Can PGN files be stored on in Windows? Any advice would be appreciated.