Go to Configuration > click Payment Gateways > Click New
Give this payment gateway a Name. It is recommended that the name has a reference to Heartland for easy selection.
In the Payment Gateway selector, select Heartland.
In Payment Gateway Settings, select either Development or Production in Account Mode depending on the organization's Heartland credentials.
Depending on the account mode selection, provide the organization's development or production Heartland Secret API Key and the Heartland Public API Key.
Finish configuring the fields in Billing Settings as preferred.