Need some help With coding a ws2812b project

Using Arduino LEDs and Multiplexing
19

And here is how I would do it

#include <FastLED.h>
#define DATA_PIN 2
#define DATA_PIN2 3
#define DATA_PIN3 4
#define NUM_LEDS 8
#define NUM_LEDS2 24
#define NUM_LEDS3 5
#define pot A1
CRGB leds[NUM_LEDS];
CRGB leds2[NUM_LEDS2];
CRGB leds3[NUM_LEDS3];
const byte button = 6;

void setup() {
    pinMode (button,INPUT_PULLUP);
    FastLED.addLeds<NEOPIXEL, DATA_PIN>(leds, NUM_LEDS);
    FastLED.addLeds<NEOPIXEL, DATA_PIN2>(leds2, NUM_LEDS2);
    FastLED.addLeds<NEOPIXEL, DATA_PIN3>(leds3, NUM_LEDS3);
    Serial.begin(9600);
}

void loop () {
    FastLED.clear();
    FastLED.show();
    int bet = selectinner();
    int wheel = outerwheel ();
    if (bet==wheel/3) win();
    else lose();
    while (button) {}
}

int selectinner () {
    int bet;
    int oldbet = NUM_LEDS;
    do {
        int potvalue = readpot();
        bet = map(potvalue,0,1023,0,NUM_LEDS-1);
        Serial.print (potvalue);
        Serial.print ("\t");
        Serial.println (bet);
        if (oldbet!=bet) {
            oldbet = bet;
            FastLED.clear();
            leds[bet] = CRGB::Blue;
            FastLED.show();
    //        delay(20);
        }
    } while (button);
    return bet;
}

int readpot() {
    int potvalue = analogRead(pot);
    for (int i=0;i<4;i++) {
        potvalue += analogRead(pot);
        delay(20);
    }
    return potvalue / 5;
}

int outerwheel () {
    const int mindelay = 50;
    const int maxdelay = 500;
    const byte spins = 7;
    int spinIt = random(255);
    spinIt = map (spinIt, 0, 255, 0, NUM_LEDS2-1);
    int maxnum = spins * NUM_LEDS2 + spinIt;
    int count = 0;
    for (byte i=0;i<spins;i++) {
        for (byte j=0;j<NUM_LEDS2;j++) {
            byte prevled = j-1;
            if (prevled<0) prevled = NUM_LEDS2 - 1;
            leds2[prevled] = CRGB::Black;
            leds2[j] = CRGB::Cyan;
            FastLED.show();
            count++;
            int vardelay = map(count,0,maxnum,mindelay,maxdelay);
            delay(vardelay);
        }
    }
    for (byte j=0;j<spinIt;j++) {
        byte prevled = j-1;
        if (prevled<0) prevled = NUM_LEDS2 - 1;
        leds2[prevled] = CRGB::Black;
        leds2[j] = CRGB::Cyan;
        FastLED.show();
        count++;
        int vardelay = map(count,0,maxnum,mindelay,maxdelay);
        delay(vardelay);
    }
    return spinIt;
}

void win() {
    for (int i=0;i<NUM_LEDS3;i++) leds3[i] = CRGB::Green;
    FastLED.show();
}

void lose () {
    for (int i=0;i<NUM_LEDS3;i++) leds3[i] = CRGB::Red;
    FastLED.show();
}

Again not tested nor compiled, there may be some mistakes but you can use it as you want.

Edit : it compiled