Check out the quick start guide video for the Interval Apple Watch Headphones.
TIP: You might want to turn off the Apple Watch passcode and wrist present sensor to make it more user friendly.
How to Use Interval with Apple Music:
I assume you have been able to pair the Interval with the Apple Watch - as demonstrated in the video above.
Now - go to your Watch app on your iPhone - and find and open Music app (below).
Then - make sure you have some music synced to your watch. Select the +Add music to manually add a song / album.
Please note: APPLE WATCH MUST BE CONNECTED TO THE CHARGER BEFORE MUSIC IS SYNCED.
Once the music is synced, you can even turn off your iPhone.
You must start the music from the watch music app -
Then - Select the music and press play. The Watch will now try to find the paired Interval.
Make sure the Interval is powered on. Music should now start to play from Interval speakers.