// Source: https://github.com/s-marley/FastLED-basics

#include <FastLED.h>

#define NUM_LEDS  18
#define LED_PIN   2

CRGB leds[NUM_LEDS];

void setup() {
  FastLED.addLeds<WS2812B, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(50);
}

void loop() {
  leds[0] = CRGB::Red;
  leds[1] = CRGB::Green;
  leds[2] = CRGB::Blue;
  FastLED.show();
}