What are the domain models to be added for a non-profit payment gateway?

See more:

C#

domain

Domain Model classes for payment gateway:
I'm currently analyzing the payment gateways like Paypal and Authorize.net for adding the domain model classes for our payment gateway. Domain Driven Design architecture was selected for our project and so right now in the process of gathering the Domain Model classes for it.
Until now I have collected some of the domain model classes as shown below:

1. Account
2. Address
3. Amount
4. Authorization
5. Capture
7. CreditCard
8. CreditCardToken
9. Refund
10. Payer
11. User

I need some more domain model classes for our payment gateway project, so please share your ideas.

Also I need some advice and suggestions for my development process because I'm new to Domain Driven Design.

Any help would be appreciable.