Board assembly is new for me so I had some help with this step. For the Feather, we went with socket female headers. For the Temperature Sensor MCP9808 (Thermometer), plain male headers were used. Check out the assembly guides for more details: Feather assembly guide and MCP9808 thermometer assembly guide.
If you're starting from scratch you will need to load the CircuitPython frimware onto your board. Start by plugging your feather into your computer with the micro USB cord. Next, use this guide to install CircuitPython onto your Feather. If you're a beginner I STRONGLY suggest doing this on Mac OS in the terminal. Keep in mind CircuitPython is in development right now, if something doesn't make sense don't give up! Post on the Adafruit message boards and they will help you.
Once you have the firmware flashed onto your board your computer should recognize it as a USB mass storage device called CIRCUITPY. Next, load the drivers for your thermometer. To do this got to the Adafruit CircuitPython repository and download the lastest CircuitPython bundle. The file should look like this
<adafruit-circuitpython-bundle-#.#.#.zip> where "#.#.#" will be the latest release number. Once downloaded, open the .zip file and drag and drop the adafruit_bus_device folder and the adafruit_mcp9808.mpy file onto your board (see picture below).
Now that you have the firmware and drivers installed, disconnect your Feather from your computer and grab your thermometer and jumper extension wires. Use the wires to connect the Feather to the thermometer following the diagram below. The VDD and GND pins will power your thermometer through the Feather. The SCL pin is the I2C clock pin and the SDA pin is the I2C data pin. Pinout diagrams for the Feather and the thermometer may be helpful at this point. If you're following my board assembly the male end of the jumper extension wires will go to the feather and the female ends will go to the thermometer.
For this step, it is important to know where your PowerSwitch Tail will plug-in in relation to your kombucha brew vessel and thermometer. For reference, my kombucha is in a cabinet about a meter away from an outlet. I used wire spool to connect my Feather to my PowerSwitch tail so it was the right length. Note: If you're using wire spool, you will have to strip the ends.
Now that you have the correct length of wire, connect pin A5 on the Feather to the PowerSwitch tail at 1: +in, tighten the screw on the top until the wire is secure. Connect the lower left ground pin (GND) to the PowerSwitch tail at 2: - in. Again, tighten the screw until the wire is secure. There are a number of pins that you can use to connect your Feather to your PowerSwitch Tail, I chose A5 because it was on the same side of the board as the ground pin. If you choose to use a different pin make sure you edit this in the code below.