Once your booking is confirmed, you can follow these steps to check-in for your flight on the airlines' website:
Locate the booking reference (PNR) number on your booking confirmation email (or under My bookings)
With the booking reference (PNR) number, you can go to the airlines' website for online check-in. You might need the following information:
First name: As per your passport
Last name: As per your passport
Booking reference: Appears in your booking confirmation
Origin: Origin city/airport as per your booking
Destination: Destination city/airport as per your booking
Email: Please use firstname.lastname@example.org (not your personal/work email address)
Once done, you may get access to your boarding pass, which you can self-print to avoid the airport hassles and queues. A few things to note:
Online check-in is usually available one or two days before departure, but it varies for every airline.
Not every airline has the option to check-in online.
If you have baggage to check or require special assistance, you will be still required to go to the airline check-in counter.
If you require a visa for the country you're travelling to, you will be required to go to the airline check-in counter for verification.