OS X Yosemite: Use a Bluetooth headset with your Mac
Use a Bluetooth enabled headset to wirelessly hear and input audio. After you pair your Mac with the headset and select it as your sound input and output device, it acts as your computer’s microphone and speakers.
See the documentation that came with your headset to pair it with your Mac.
After you paired your headset with your Mac, click the Bluetooth status icon in the menu bar, choose the headset you want to use, then choose Connect. The headset is automatically used as the sound output device for your computer.
If the Bluetooth status icon isn’t visible, choose Apple menu > System Preferences, click Bluetooth, then select “Show Bluetooth in menu bar.”
Some apps, including Messages, allow you to select an audio device from within the app (independent of the audio input and output devices selected in Sound preferences). To use a Bluetooth headset with Messages, select the headset in the Audio/Video pane of Messages preferences.