1. Press and hold the power button for more than 7 seconds while the headphones are turn off.
2. You will see the led light in the phone blinking red and blue alternately.
3. Now in the Mac, open System Preferences -> Bluetooth and turn the bluetooth on if it is not. You should see the MDR-ZX780DC in the list. Click pair for this device.
4. You should be ready to use it. If it is connected but you hear no sound, check at System Preferences -> Sound if MDR-ZX780DC is selected is the default output.