So you can design and implement a complex automated system implementing your own logic, a 3rd party API and a payment service. But this, you didn't understand

So you can design and implement a complex automated system implementing your own logic, a 3rd party API and a payment service. But this, you didn't understand before doing so? Do you get you are on HN, not facebook, and therefor people may doubt your sincerity on this point? Just to save you a marketing shaped comment as a response, it's rhetorical.