You can use the Heart Rate Zone Trainer any time you want to do some exercise, and be aware of your heart rate and the zone percentage you're in. Set it on a surface where you can see it easily, and pay attention to how long you are in different heart rate training zones.
Plug in the battery (or a USB power cable).
The display will show the intro text "b.P.M." and "Prct" so you know which display is used for what.
Next, your max heart rate is displayed, in this case, 180.
The device will start scanning for a BLE heart rate monitor, displaying "SCAN bLE".
Turn on the heart rate monitor and strap it to your inner arm. At first the displays will show "...." as it connects, and "----" as the first zero bpm values are sent.
BPM and Percentage of Max Heart Rate
As the Heart Rate Monitor sends values, the Feather will display the bpm on top and the percentage of max on the bottom.
You can do some jumping jacks or run around a bit to get your heart rate up.
Here's an action video -- you'll see the rate going up as I ran for a few minutes.