Arduino-Voltage-Monitor

I've used the following github repositories:

https://github.com/sweebee/Arduino-home-automation/blob/master/libraries/readVcc/readVcc.h

https://github.com/adafruit/Adafruit_SSD1306

https://github.com/adafruit/Adafruit-GFX-Library

but I don't know how to link to them from my project.