Since your question was't specific to PocketMine, imma link you to here: http://php.net/manual/en/language.oop5.php
thats php learning and i know php i want to know how to make pocketmine read more than one class in my plugin
Declare a class in one of your plugin's PHP files that are loaded. PHP: class Example {} PocketMine (PHP) read it.
PHP: namespace some/name/space { class Main { $this->secondClass = new SecondClass(); } class SecondClass { }} NOTICE: Don't tell me this doesn't work, this is just an simple example meaning if you know PHP you should understand this with no problem!