You can use:
Airlines' official websites (e.g., Qatar Airways, Emirates)
Online travel agencies (e.g., MakeMyTrip, Expedia, Skyscanner, Google Flights, Kayak)
Mobile apps (e.g., Cleartrip, Hopper)
Fill in the search form:
From: Your departure city or airport
To: Your destination
Departure date (and return date if round-trip)
Number of passengers
Class: Economy, Business, First Class
Then click Search or Find Flights.
Browse through options and compare:
Flight times
Prices
Airlines
Stopovers or direct flights
Baggage policies
Click on the flight you want to book and review:
Flight duration
Layover time (if any)
Cancellation/change policies
Then click "Continue" or "Book Now".
You’ll be asked for:
Full name (as per passport or ID)
Gender
Date of birth
Passport number (for international travel)
Nationality
Contact info (email & phone)
You can usually add:
Extra baggage
Travel insurance
Meal preferences
Seat selection