How to update zcash4mac w/latest version of Zcashd?

Forgive the ignorance, my Unix is 20 years old and 99.9% forgotten.

DL’d the original zcash4mac but the version of zcashd it is running remains 1.0.4 (same version is installed with the zcash4mac currently available for DL). How can I update? Step by step instructions would be very helpful for essentially a Unix noob.