Download a zipfile from github using the "Download ZIP" button and install it using the IDE ("Sketch" -> "Include Library" -> "Add .ZIP Library...", OR:
To turn off the blue LED, you must call epd_poweroff_all(), which will turn off the entire power supply controlled by PWM_EN. Note that it cannot be turned off when powered by USB. It can only be turned off when powered by battery. For details, refer to <examples/demo>