Additional information:
Go to the United Airlines website www.united.com.
Start the flight booking process by entering your desired departure city, destination, and travel dates.
When you reach the payment page, look for the option to redeem a travel certificate (usually listed as "Travel Certificate" or "Voucher").
Enter your certificate number and any other requested details, such as the PIN or security code if applicable.
The amount on your travel certificate will be applied to the cost of the flight.
