Importing and running already installed game files

Hi…really new to Lutris so forgive me if i’m asking already answered questions.

I have a PC with games already installed on it and i have games i’ll like to play on Lutris via my Chromebook. I have already imported 2 games as a test ( Halo and Guild Wars 1) into my Linux folder in my Chromebook.

Could someone point me to how i can get Lutris to recognise those files?

There is a small arrow next to the Install button when you select a game in the list. When clicked you see an option to locate an installed game.