How to make a my plugin a phar file?

Recently,I have been working on trying to make basic plugins.
Though there's something bothering me...Every Plugin on pocketmine end with .phar but I was making .php .How should I change this?

DevTools has the command /makeplugin <pluginName> that will convert your plugin into a .phar file.

Oh thanks.I'm gonna try tonight!

Yeah, also make it look like this project structure, otherwise it'll say something like invalid name check the case. Also if you have to reload the plugin you have to /stop the server and then start it again.