functions.php: Helper functions to generate signature string and call requests to WPC service.initiate.php: Initiate the payment.return.php: Get transaction details (return callback url).cancel.php: The buyer cancel the payment (cancel call back url).Open files initiate.php (customize_initiate.php if you want to work with demo 2) and return.php and change your the config by your merchant config values
Then, run the demo to understand the payment flow.
Click here to initiate the payment
customize_index.php: Initiate the payment with demo form.customize_initiate.php: Process demo form.