Register for an account with Stripe Payments and you will be given some API keys which you need to enter into your settings area. There are two types of keys: “TEST/DEV” and “LIVE”. You’ll test out your c4rt in “TEST/DEV” mode and once you’ve launched you can then add your “LIVE” keys (and take live online payments at 0% – minus the tiny bit that Stripe takes – the “standard bank charges” bit).