// you have to include the library
# include <Adafruit_NeoPixel.h>

// and where the strip is hooked up on the Arduino
# define PIXEL_PIN    6

// how many pixels on the strip?
# define N_LEDS 20

// make the neopixel object.
// here I use NEO_GRB + NEO_KHZ800.  that's typical, but must match the strip you have
// it is called myStrip. Most just call it "strip"

Adafruit_NeoPixel myStrip(N_LEDS, PIXEL_PIN, NEO_GRB + NEO_KHZ800);

void setup() {
// in your setup, make one call to the begin method

  myStrip.begin();
}

void loop() {
// in your code, change any pixel's color
// pixel number: NN from 0 to the end of the strip (NLEDS - 1) in this example 0..19
// red level: redBrightness  0 off to - 255 full brightness red
// green level: greenBrightness
// red level: blueBrightness

  int NN = 4;                 // some pixel
  byte redBrightness = 128;   // half bright red +
  byte greenBrightness = 0; // no green +
  byte blueBrightness = 255;  // full bright blue

  myStrip.setPixelColor(NN, redBrightness,  greenBrightness,  blueBrightness);

// when you have set all the pixel colors, the call to show will update the physical strip:

    myStrip.show();
}