Once you have purchased your ticket the airline website is generally the best place find further information on your baggage inclusions. In the airline matrix below you should find the airline you are flying with, click on "manage your booking" to go through to the appropriate airline website.
You will need the airline booking reference number (highlighted in the below screen shot on your booking confirmation) and email address that was used to make the booking. For some airlines like Air Asia you will need to contact the airline directly.

Baggage allowances and policies differ by airline, if you need additional baggage we recommend you add baggage online prior to your travel as some airlines charge additional fees for adding baggage at the airport.
In the airline matrix below you should find the airline you are flying with, click on "manage your booking" and the airline website will advise on how to book additional baggage.
You will need the airline booking reference number (highlighted in the below screen shot on your booking confirmation) and email address that was used to make the booking. For some airlines like Air Asia you will need to contact the airline directly.

Please Note: If your airline is not listed on this page, please refer to that carrier's website to manage your booking as the below list is not exhaustive.