In case you are in possession of the required acquiring contract and the payment method is activated at Sage Pay you have to create the corresponding connector configuration in your account under Space > Configuration > Connectors

In case you want to test the integration first you find test credit card numbers on the Sage Pay Testing website located here: http://www.sagepay.co.uk/support/12/36/test-card-details-for-your-test-transactions

In order to test the payment connector the following section contain test data. For some tests special instructions have to follow. Some test data may produce a negative result. We indicate when the test data should lead to a transaction failure or decline.