It's not copy and paste. Stripe Checkout does not even take a payment. All it does is present the UI to collect information, then returns a token to your page via a hidden form field. You must then write code to accept the form submission, use Stripe's API to make a charge against the token you received, send receipts and deliver the product.
Here's the Stripe Checkout integration guide for Rails for example: https://stripe.com/docs/checkout/guides/rails