Press and hold the rear button. The rear button can be found on the back of your AirPods case. Once you press and hold this button, you'll initiate the pairing mode.
Open System Preferences and click on Bluetooth.
Once you've navigated over to this screen, you should see a list of available devices. Select AirPods.
Pair your AirPods.
Once you've selected AirPods from the Bluetooth menu, the earbuds should be paired, and you should now be connected!