Or add sounds?

I figured out how to add environmental effects like fog, rain, etc, but when I go to

Atmosphere<Varia<Sound

there are options for Ambient Sound and Music, but instead of the Resources button there is an X so I can't pull any resources. Any idea what I'm doing wrong?

I also tried to create local sounds using a PointSoundTrigger, but it won't let me add sound to the trigger or adjust volume/range etc.

Any ideas?
Thanks!