The sooner you book your flight, the better your chances of selecting a window seat. Most airlines allow you to choose your seat when you book your ticket.
Web check-in opens 24 to 48 hours before the flight. Log in as soon as it opens to choose your seat.
Go to the airline's official website and look for the "Web Check-In" or "Online Check-In" tab, usually found on the homepage.
Provide your booking reference number/PNR and last name, then click on Check-In to retrieve your booking details.
Choose the passengers you want to check in for the flight. After that, you get the option to select your preferred seats.
Here you get the option to select a window seat if available. You have to pay additional fees for this.
Do not forget to download your boarding pass or have it sent to your email or mobile device.