Hi David,
To install it just unzip to your add-on scenery folder - it will sort the rest out for you, then boot-up FS on the main screen (create flight, select flight, lessons etc.....)
There should "settings" at the bottom of the page, then go to scenery library, add area and browse to the folder named "nica" click add for that folder.
FS Will tell you to restart, do that, reload and go to Nice.
You SHOULD see a difference - I did (with settings quite low too)
Hope this helps and Happy Flying

Carl out.....