Hi @kristeller, welcome to the forum! 
Cool! 
I’d recommend referring to the guides section of our Basic ESC product page, to get an overview of the PWM signals the ESC expects to be sent for initialisation and control, and how it responds to them. This comment may also be relevant.
The ArduPilot PCA9685 library may be worth referring to for some functions you may want to implement and use, but it’s written in C++, and is likely more complicated than is required for your purposes. I expect there is also example code available from Adafruit for at least getting the hat up and running.