Free shipping, you set in admin> "Payment and shipping method"> "Order total"> "Shipping". Click change.
"Allow Free Shipping" you set to "true".
In "Free Shipping For Orders Over" you specify from which amount you want free shipping.
On "Provide Free Shipping For Orders Made", you specify whether free shipping should apply nationally, internationally or both.
What do I do when I no longer want to offer free shipping?
You go to admin> "Payment and shipping method"> "Order total"> "Shipping" and click on change.
Then set "Allow Free Shipping" to "false".
Then click "Refresh".