To book a flight on United Airlines, you can follow these steps:

·         Visit the United Airlines website (www.faresmatch.com)

·         Click on the "Book" tab and select "Flights"

·         Enter your departure and arrival cities, travel dates, and number of passengers

·         Choose your preferred flight(s) and select "Continue to Booking"

·         Enter your passenger and payment information and review your booking details

·         Confirm your booking and pay for your flight.

You can also book a flight by calling United Airlines reservations at +1-800-918-3039 (within the US) or the local United reservation office in your country.