To book a flight with Southwest Airlines, visit their website or mobile app. Enter your departure and destination cities, travel dates, and the number of passengers. Browse through available flights, considering factors like departure times, prices, and layovers. Select your preferred flight and proceed to provide passenger information, southwest Airlines flight reservations including names and contact details. Complete the booking by entering payment details, such as credit/debit card information. After confirmation, you'll receive a booking confirmation via email for your upcoming Southwest Airlines flight.