You can check to see if you have any unused travel credits right from the Flights tab while on the Travel page:
This will allow you to see this information before you even begin to search for your flights. At this time travel credits can be redeemed by contacting TravelBank's travel support.
When you click "View Credit" you can see the flight credit details:
You may also view your flight credits on the My Account page, this information will be in a pane located below your loyalty programs: