how to integrate api in website

Hello please help I need someone who knows the programming About how to integrate api in website I have website and sell products For musicians I have a bank account online like paypal its www.epay.com they asked me i must to integrate with Epay SCI successfully then i can use epay to collect money from customers. they Give me Instructions , but I did not understand anything.
These are the instructions:
Please follow below steps to apply for an Epay merchant:

1. go to https://www.epay.com/about_activity.html , click "Get Started"

2. login your epay account, "click to Integrate SCI"

3. fill up required information and submit

4. Enable API(disable "receive money" and "send money") by clicking "user information" - "account security "

5. download API/SCI documents here https://www.epay.com/api.html , fill in the SCI parameter info

6. check whether the integration is successfully completed. If successfully integrate Epay SCI，shown as attached pic
After SCI integrated successfully, you can apply $10 merchant awards, at the same time we will review your application and get back to you the result within 1-3 working days.
can someone help me please? my site Designed on wordpress
thanks.