...
Firstly, admin click on Stores > Configuration > Sales > Payment Methods.
For General Settings:
In addition, admin can set information for: Title Title, PSPID, User Id, Password, SHA-in pass phrase, SHA-out pass phrase, Hash algorithm, Default Settlement Currency, Payment Description, Language Code, Payment Action, New Order Status, Sandbox Mode Enabled, Url Production, Url Maintenance Production, Email Customer, Payment Instructions Helper, Button Button BG Color, Button Button text Color.
For Barclay ePDQ Hosted Payment Page( HPP) integration:
For Barclay ePDQ Direct Link Integration:
All of instructions of how to get the needed information are right under each field.
...