Slide Switch Wires
In order to power the circuit on and off, the slide switch will need to be connected to the Adafruit Feather. We'll need to two pieces of wire. These wires can about the length of the board.
Using wire stripper, remove a bit of insulation from the tips of each wire. These 30AWG silicone covered wires are stranded, so it's a good idea to tin them with a bit of solder. This will make it easier to connect them to the switch and it prevents the strands from fraying.
Solder Wires to Switch
We only need two out of the three terminals on the slide switch. Using wire cutters, snip one of the pins – either the far left or right but not the middle! You can also trim them short, about half their length is good. Add a bit of solder to the two short terminals and solder the wires to them. A helping third hand is great for keeping the switch steady while soldering wires.
Connect Switch to Feather
With the switch now connected to the wires, you can solder them to the EN (enable) and GND (ground) pins on the Adafruit Feather. I normally tin the through-holes with a bit of solder before adding wires. A PCB vise like the Panavisr Jr is great for holding the board up while soldering.