Assuming you have built packageable Salesforce configuration and code in a Developer Edition and want to package it as 2GP for distribution on AppExchange, these are the steps to take:

<aside> ℹ️ Additional reading: https://hutte.io/trails/1gp-vs-2gp-managed-packages/

</aside>

Part 1: Get ready for Git-based, Scratch Org based Salesforce Package Development

Part 2: Create, promote and install your first 2nd generation package version

Part 3: Improve your time-to-market and product development efficiency with automation