There are a couple of things you need for mining monero in osx using xmring:

1) A monero wallet (get one from mymonero.com)
2) Homebrew (brew.sh)

mining monero in osx using xmring: dependencies

You have to make sure you have homebrew installed (so that you can install the xmrig dependencies), and you need a wallet to put your mined monero in and keep them safe.