Payment for services using Internet acquiring. How to make your own form?

Question

Payment systems

Colleagues, good afternoon.
Interested in the following question. I searched a lot for such information, but really did not find anything suitable for explanations.
There is an agreement with Internet acquiring of Tinkoff Bank.
There is one BUT: they offer the following: Link the site with buttons for payments through their widget or integrate a payment module.
For the third option, it is suggested that the programmer himself write the code to transfer information to the acquirer.
What I need:
1. The amount must be entered manually (Required field).
2. Full name of the customer (Required field).
3. E-mail or Phone (Required field).
Accordingly, all this data should go to the equalizer.
They provide their own API. I'm just not a programmer, and I would be grateful if someone shares their experience or tells how this can be done, some literature