A detailed description is available on the Amazon Developer site.
https://developer.amazon.com/public/support/submitting-your-app/tech-docs/appstore-understanding-submission#high-level-review-of-prerequisites
Very helpful is also the App testing service.
https://developer.amazon.com/app-testing-service
-UPDATE-
Upload a new Version of the App:
https://developer.amazon.com/public/support/submitting-your-app/tech-docs/updating-binary-apks-for-a-published-app#add_binary
Here a log on my first release with some lessons learned:
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