YOU CAN READ MORE ABOUT WHAT APPLIES TO BAGGAGE HERE.
If you have not purchased checked baggage when you made your booking, this is booked directly with the respective airline. You log in to your booking with the airline's booking number (see flight ticket). The prices for checked baggage vary for each airline and each trip.
Note: In most cases, it is more expensive to pay for baggage at the airport. So our recommendation is to book this service in advance, either together with your booking or directly on the airline's own website before departure.