look up fadecandy, pixelpusher and ledlab if you want something fancy like that.
If you are ready instead to control your LEDs, look up fastLED or Adafruit neopixel LED library.
I also am writting a LED library called FAB_LED.
With my library, you'll need to declare the LED strip you're using, a pixel array, update the pixels and then write the array to the LED strip, for example:
ws2812b<D,6> strip;
grb pix[numPixels];
for(int i=0; i < numPixels; i++) {
pix.red = random(255);
pix.green = random(255);
pix.blue = random(255);
}
strip.draw(numPix, pix);
delay(1000);