Credit card payment by USAepay

I want to use USAepay for credit card transactions in my desktop application.
i never did this kind of work before.
Does anyone has any sample code or guid?

Their API looks very straight forward to implement and they have a bunch of examples I saw.

I haven’t seen any plugins for this, but if you take a stab using HTTPS sockets you can implement this yourself.

Thanks for your replies.
I am new to xojo. i have gave post https call api but not working. i found following example on USAepay site.

curl -X POST
-H “Content-Type: application/json”
-H “Authorization: Basic X1Y4N1F0YjUxM0NkM3ZhYk03UkMwVGJ0SldlU284cDc6czIvYWJjZGVmZ2hpamtsbW5vcC9iNzRjMmZhOTFmYjBhMDk3NTVlMzc3ZWU4ZTIwYWE4NmQyYjkyYzNkMmYyNzcyODBkYjU5NWY2MzZiYjE5MGU2”
“command”: “cc:sale”,
“amount”: “5.00”,
“amount_detail”: {
“tax”: “1.00”,
“tip”: “0.50”
“creditcard”: {
“cardholder”: “John Doe”,
“number”: “4000100011112224”,
“expiration”: “0919”,
“cvc”: “123”,
“avs_street”: “1234 Main”,
“avs_zip”: “12345”
“invoice”: “12356”

I am not getting how can i call this using httpSocket.
Can any please help me to process above request using HttpSocket?