I don't see the point of giving bad reviews for someone's lack of experience. Although this resource is, rather... unusual and practically not usable; you can improve it and make it into something better with effort. I'd suggest running a local test server (basically a minecraft server with paper/spigot/bukkit or whatever core you wish but in your local machine) and test your plugins before publishing and even using.
Best of luck developing plugins!
(P.S: If you require help setting up the local server, shoot me a DM. I may not know Java much but I can help you with basic setups)
Doesn't work, the command is not registered in the Main class. If you're going to publish a plugin, TEST it, you can just make a local server. It's not hard to test it. I get you are new but this is basic things you should know before publishing a plugin.