#include "FastLED.h"

// How many leds in your strip?
#define NUM_LEDS 256

#define DATA_PIN 3

// Define the array of leds
CRGB leds[NUM_LEDS];

void setup() {
  FastLED.addLeds<WS2812B, DATA_PIN, GRB>(leds, NUM_LEDS);

}
void loop()

{

  for (int dot = 0; dot < NUM_LEDS; dot++)

  { leds[dot] = CRGB::Red;

    FastLED.show();

    leds[dot] = CRGB::Black;

    delay(300);

  }

}