Alright, stupid question AHOY!

This file that ggn gave me is a .prg file, can I open this in STeem?  I would love to open it on my old Atari but it died many years ago and is now just a pretty box covered in fist-prints (due to anger/abuse).

I tried opening this in STeem but it is not showing up.  I also tried changing the extension to .ST but that was a dumb idea too.

BTW, what is 'falcon fixing'?  Sounds sweet  :o