Alright. Fun time.
In order to create an analog signal we can control, we will connect a potentiometer to the Circuit Playground. By connecting the ends of the potentiometer to the 3.3V and GND there will be a variable voltage on the middle (sweep) pin.
The test circuit can also be setup on a breadboard as shown below. You can go this route if you want, like if you already have some of these parts, but the knob on the panel mount potentiometer is bigger and easier to work with.