Nostalrius Begins - Quality wow vanilla realm (1.12)

I just acquired a macbook pro from an uncle and I have no clue how to use macs. I am unsure what year it is or anything but I was hoping that someone could help me with the downloading process of add ons.

If you could give me steps or send a link that will give me the whole nine years on how to do so, I would be much appreciated

Thanks in advance!

-Beefy

just download an addon.zip an extract it (double click)
then copy the new folder in your wow/interface/addons folder