Arena might not be the easiest GUI to use, but it does have a decent Help File.
Arena comes with a few pre-installed engines, but if you want to use the Komodo engine, you'll have to install it into Arena.
If all you want to do is look at the PGN file of your game, you shouldn't need an engine at all. Just open the PGN file with Arena, and you should be able to scroll through the moves of the game.
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