The Notifications API for Alexa Skills is currently in an expanded developer preview and the team isn't onboarding any new developers regarding this. Keep an eye out on the developer blog for more details on this in the future. For AVS related questions, I'd reach out on the AVS forums here.
I read the document about "push notification" like: https://developer.amazon.com/docs/alexa-voice-service/notifications-overview.html and find out information about it but i do not know how to use it.
Can someone help me, please?