example:
// LEDs
/**********************************

• Information LEDs blinking
  ***********************************/
  // If one of the following is defined here, or in the sketch, the pin will be used for the
  // corresponding led function.
  // They have to be enabled here (or in your sketch). Replace x with the pin number you have the LED on.
  //
  // NOTE!! that on some platforms (for example sensebender GW) the hardware variant can enable LEDs by default,
  // These defaults can be overridden by defining one of these.
  #define MY_DEFAULT_ERR_LED_PIN 9
  #define MY_DEFAULT_TX_LED_PIN 6
  #define MY_DEFAULT_RX_LED_PIN 5

to one WS2812B LED using Adafruit neopixel or FastLED library?

Regards,

MiKa