This is sample code for a workshop building a lantern in a Ball jar with an Adafruit NeoPixel and Gemma board.
Adafruit's Arduino IDE is needed to upload the code to a Gemma or Trinket (Arduino-compatible) board.
https://learn.adafruit.com/introducing-trinket/setting-up-with-arduino-ide
This will not run on a Mac unless you change System Preferences / Security & Privacy / General / "Allow applications downloaded from:" to Anywhere.
The Adafruit Arduino IDE includes the NeoPixel library, but if you are using a different board and the standard IDE, download the library from:
https://github.com/adafruit/Adafruit_NeoPixel
To learn all about NeoPixels, read Adafruit's NeoPixel Überguide.