A few various questions... plz help

I bought napoleon total war in a store, so I have the discs, yet when the game is installed, it runs through steam.
SO, since the game is running through steam, HOW do I access files to the game, such as lua. and /data so I can configure (specifically disable fog of war) and install addons?

Napoleon total war files are not anywhere to be found on my computer an I cannot figure out how to access them.

Thanks in advance

Just follow this:

C:\Program Files\Steam\SteamApps\common\napoleon total war\data