You need a payment provider. A lot of that. The most popular worldwide are Paypal, Stripe, Braintree, others. You can find local providers if you're outside the USA.
You need to check the API documentation of the selected provider. A lot of them have public API docs and links you can find on the landing pages. Usually, this is REST API, so you can use the Requests library to make the integration. Don't forget to write integrational tests!
You need to be compliant with the rules and policies of the selected provider.
You need to have a bank account to make a settlement from the payment provider.
Most providers have a sandbox to test API without having a real production-approved account.

When I said, "You need..." I mean you or your company needs to provide such information or create a needed account(s), bank accounts, etc.
I need to implement payment with credit card in a Django Project. But, I don't know how to start, and I can't find any information about do it.

What's the best module to do the integration?
The module is well documented? and it has code examples about the correct implementation.

Please, if you know how to do it, help me. I'm collaborating with an ONG and we need to implement this for donations payments.
Thanks. Regards,
Credit card payment in Django (Python) with RedSys