Those little plastic caps slide off, forward or backwards,can't recall which direction.
Slide it then lift it with a finger nail. Easy.
Under each one you'll find a 6mm captive nut. Make sure your screws/bolts are the correct length
otherwise they will bottom-out and not secure properly. Use some copper grease on the threads.
Don't try to remove the long black trims, there's nothing under there anyway.
Hope this helps.