Wont display

Can Anyone help me? I have never used var_dump. I know about the function but I dont know where to place it in my code.

Someone told me to update $this->orange with var_dump but I honestly just dont know how ive researched the function and tried multiple ways please help heres my code:

PHP:

<?php

namespace Test;

use pocketmine\event\Listener;
use pocketmine\event\player\PlayerJoinEvent;
use pocketmine\event\player\PlayerInteractEvent;
use pocketmine\plugin\PluginBase;
use pocketmine\Server;
use pocketmine\Player;

class Main extends PluginBase implements Listener{

public $orange = [];

public $blue = [];

public $red = [];

    public function onEnable() {
        $this->getServer()->getPluginManager()->registerEvents($this, $this);
    }

    public function onJoin(PlayerJoinEvent $event) {
    $orange = $this->orange;
    $player = $event->getPlayer();
    $uuid = $player->getUniqueId();
    $playerCount = count($this->getServer()->getOnlinePlayers());
        if ($playerCount <= 1  ) {
            $orange[] = $uuid;
        }
    }
   
    public function onInteract(PlayerInteractEvent $event) {
        $player = $event->getPlayer();
        $uuid = $player->getUniqueId();
        $orange = $this->orange;
        if ($event->getItem()->getId() == 1) {
            if (in_array($uuid, $orange)) {
                $player->sendMessage("Hey!");
               
            }else {
                $player->sendMessage("L");
            }
        }
    }
}


Basically, I dont know where to add the var_dump()

In my code thanks.

 

var_dump($this->orange); ?