Suggestions on implementing credit card payment?

Hello everybody and thank you for your attention,
as specified in the discussion title I'm trying to use a credit card system on my hikashop ecommerce. I already have the code that communicate with the bank server and that will do everything, the data should be passed by curl to the server and that's all, but I'd need some suggestion on how and where put the code to use this stuff, I don't know if it makes some difference but I have the business version,

thank you again and cheers