But there's more you can learn. If you are interested to learn further on how PocketMine-MP plugin works, you can see the source code of Poggit plugins.
If you don't understand something, you could try checking the PocketMine-MP Documentation and the Doxygen first. If that doesn't help you, you can ask in our Discord server or in the PMMP Discord server.
Anyways, thanks for using PocketMine School. We kindly apologize for any mistakes, and we welcome everyone to contribute to the GitHub Repository or to report an issue. We are looking to keep improving PocketMine School, so please let us know if you have any ideas.