Components of the Circuit

This circuit only needs:

It is assumed that the board is powered through a USB cable (not shown in the circuit diagram).

Layout of the Circuit

Attach one of the GND pins on the Arduino to the GND bus of the breadboard.

Attach the 5V output pin of the Arduino to the power bus of the breadboard.

Attach the center pin of the slide switch to the power bus.

Attach each of the other pins of the slide switch to one side of a 10KΩ
resistor; attach the other side of the resistor to the GND bus. Since one
side of these resistors is attached to GND, they are called “pull-down” resistors.
They ensure that when the switch does not activate one side, then that side
has a well-defined voltage, i.e., 0V.

Also attach each of the the non-center pins of the slide switch to one of the
digital pins on the Arduino.

Install 2 LEDs in the same way shown in the packet on External LEDs,
i.e., attach the positive side to one of the digital pins on the Arduino,
and attach the negative side to a small (330Ω) resistor; then attach the other
side of that resistor to ground.

A Slide Switch with Two LEDs