How do I even use this package?

[JoaoHCopetti]

The documentation is not clear to me.

It only shows this code:

Notifications.postLocalNotification({
    title: "Local notification",
    body: "This notification was generated by the app!",
    extra: "data"
});

Ok, how do I handle the user request permission? How do I define the notification channels? Or how do I inform the channel? Should I create it myself or this package does these things to me? At least inform these kind of stuff in the documentation.