To change a guest's name, you need to open the reservation data on Booking.com. You can do this in several ways:
1. Open the booking confirmation email and click on the "Modify your booking" button, which will take you to a web page with booking details.
2. Follow this link, enter your PIN and confirmation number in the specified fields and click "Next".
3. Log in to your Booking.com account, open the "Bookings" section, and select the desired hotel. Click the "View Booking" button.
4. On the booking details page, find the "Room Information" section (above the "Important Information" section).
5. Here you will see the name under which the reservation was made, and to the right of it, you will find the "Edit" button. Click on this button, enter the desired name and confirm the changes by clicking on the "Save" button.
6. You should then receive an email confirming the changes.