Integrating Payment Gateway with Navision Ver3.6

Dear All, Can anybody help me out, how to integrate Navision 3.6 with Payment gateway? To explain in brief about payment gateway… We have a Service Provider who provides the Payment Facility and also he provided the API for development. So how do i integrate Navision With the Payment Gateway.What are the software and hardware requirements? Please do help me, if any one has some idea or implemented the same. Thanx in advance… Vijay