To utilize your JetBlue Travel Credit to book a flight, you can follow these steps:

1. Log in to your JetBlue account at jetblue.com.
2. Search for the flight you want to book.
3. On the payment page, select "Use Travel Bank or Credits" as your payment method.
4. Enter your Travel Bank or Travel Credit confirmation number, along with the security code and the name on the card, if applicable.
5. Click "Apply" to apply your Travel Credit to your booking.
6. Review your booking and make any necessary changes.
7. Click "Submit" to complete your booking.

Please note that JetBlue Travel Credit is valid for one year from the date of issuance and can only be used for JetBlue flights. If the cost of your flight is greater than your Travel Credit, you will need to pay the difference with a credit card or other payment method. If you have any further questions, you can contact JetBlue customer service for assistance.