Go to "Monetization" --> "Payment Gateway" in your CMS.
Click on PAYGATE (See Below Screenshot)
Type the “3D Secure ID”, “3D Secure Password”, “Non-3D Secure ID”, “Non-3D Secure Password” (Which you have received after you signed up with PAYGATE in the corresponding fields.
Finally, click on "Integrate Payment Gateway".
Note:
This Payment Gateway supports payment methods i.e. Subscription. It doesn't support onetime payment methods including PPV, PPV Bundle and Pre-Order.