The diagram below provides a general visual reference for wiring of the components once you get to the Assembly page. This diagram was created using the software package Fritzing.

Adafruit Library for Fritzing

Adafruit uses the Adafruit's Fritzing parts library to create circuit diagrams for projects. You can download the library or just grab individual parts. Get the library and parts from GitHub - Adafruit Fritzing Parts.

The diagram for the driver circuit is shown above on a FeatherWing Proto board.
The red LED is a stand-in for the alarm.

The circuit uses pin D10 of the Feather through a resistor to the left leg of the transistor (base) in order to toggle when the transistor opens or closes the middle leg (collector), which allows the alarm circuit to go to ground via the right leg (emitter).

The middle leg connects to the any Ground pin.

The right leg connects to the USB pin.