You can run a test transaction by following the instructions in the manual transactions support page by using a test credit card to process the transaction. A common test credit card is this Visa credit card:
Card Type: Visa
Card Number: 4111 1111 1111 1111
Card Expiry: Any valid expiry date in the future
Card CCV: 123
Then click ‘New Transaction’ and wait for the page to refresh and a receipt to appear. You want the receipt to show ‘Declined’, as this means it has made contact with the bank and has been rejected because it’s not a real credit card. If the receipt returns back ‘Error’, it means there is an issue with your account. Double check your transaction password and try again. If this doesn’t work, please contact support.