Random

How to use random function ?

PHP:

public function myFunction(){
    echo "Hello!";
}

//and e.g. in a join event:

public function onJoin(PlayerJoinEvent $e){
    $this->myFunction(); //this calls myFunction
}

I think he thinks on random teleport

hm or function mt_rand()

https://php.net/mt-rand

How to use this code for the random particles ?

i don't understand

Look at this random teleportation code: https://github.com/Artide/PM-1.5-Plugins/blob/master/RandTeleport/src/RandTeleport/Main.php

You need to be more descriptive, and what's random function? Use your brain and read: http://php.net/manual/en/function.mt-rand.php

PHP:

<?php
public function getRandomFunction($num1,$num2){
$rand = mt_rand($num1,$num2);
}
public function onJoin(PlayerJoinEvent $e){
$rand = $this->getRandomFunction(1,5);
switch($rand){
case 1:
//code
break;
case 2:
//2 code
break;
/* etc... */
}
}

PHP:

public function getRandomFunction($num1,$num2){
$rand = mt_rand($num1,$num2);
return $rand;//gotta return to make the function run
}