What is Reformed Theology/Calvinism 2: God's Sovereignty & Man's Responsibility

If God is sovereign over all things & predestines all that comes to pass then why does He still hold man responsible for their sin? What is the difference between man having free will & man being a free moral agent? Does the Bible say man has libertarian free will or does it teach free moral agency? Is God the author of sin if He predestined it or decree for it to happen? What is compatibility & concursus/concurrence & why are they so important to understand?