Payment gateway integration in Wordpress

I have a wordpress website, booking system. I am using Wordpress Plugin. called Booking calendar. [login to view URL] I want to add the another payment gateway called Moneris. Will share the API and website link in Private chat. It will requires PHP coding on Wordpress website, not a customizing. It will take about less than 15 working hours. Please let me know if you are familiar with Wordpress and PHP coding, payment integration. Thanks