Trying to use this package , any instructions on what to do

Trying to use this package , any instructions on what to do , have downloaded the package, run the makefile in a terminal which seems to have worked, but don't see anything happening? Samsung x240 and mint 20. looking to control backlight
Linux novice What are the hotkeys for controlling the backlight? I see the XF86Launch1 and 2 but don't which keys they are

allan