Set URL to the file

The feature of loading chess games from a PGN file is not officially supported by the wordpress plugin.

However the unsupported extended option feature could be used for that purpose as described in a note at the bottom of the wiki page:
https://sourceforge.net/p/pgn4web/wiki/User_Notes_wordpress/

FAQ: how to use the plugin with PGN files?
The supported setup requires providing the PGN data within the [pgn] … [/pgn] tag as described above, however the plugin can also be used with PGN files; although not a supported feature, the following instructions might help:
– make sure a PGN file is available on the same server as the plugin; assume for example the PGN file is available as /games/games.pgn
– enter the following code in your post: [pgn eo=t pd=/games/live.pgn] [/pgn]

Keep in mind, unsupported features are not supported and might stop working in future releases of the plugin.

thanks and one more question.
Is it possible to use fen codes in your plugin and how?

Please do not mix completely different questions into a single topic, it makes it very difficult to follow.

Yes, you can use FEN positions with the plugin, provided you use the FEN tag as specified with the PGN standard (see FEN header tag).

The main pgn4web package at https://pgn4web-downloads.casaschi.net contains several example of FEN positions within PGN files.