For mechanical assembly, follow the instructions at http://tote.readthedocs.io/en/latest/assembly_v5.html#legs
Solder the headers, PWM chip and resistors onto the board. Add the power switch and battery holder. Connect the servo plugs.
Copy the python code from project's repository onto your D1 Mini using Adafruit's Ampy utility. Plug the D1 Mini into the PCB.
Use the D1 Mini's headers to add shields with sensors and other components to the robot. Modify the code to take advantage of them.