As we do on Smartphones, we have to enable Developer Options in the Wearable to be able to access it with adb. To do so, go into Settings panel, then into “About”; Tap into “Compilation Number” 7 times. A toast should appear indicating that Development options are enabled. Then inside “Settings”, a new panel called “Development Options” will appear, and there we can enable “ADB Debugging” and “Bluetooth debugging”.
Now it is time to plug in the wearable into the USB port and execute “adb devices” in a terminal. The device might appear as unauthorized. To fix that, note that a permission dialog has appeared on your smartphone (not on the wearable) asking you for permission to let this computer install Apps into the Wearable. Accept it and execute “adb devices” again. The device should now appear just fine.