If you want to cancel your trip you can do it in 2 ways: the first way will be through the my trips option, in this option you can access all your trips and by clicking on it you can choose the cancel button. Another way to cancel or change your trip is to contact customer service. 

Depending on the airline you will have to pay a fee for your luggage, not all of them charge you for it. And those who will charge you, you will not have the price of the extra luggage on your ticket and you will have to pay it when checking in at the airport. 

If you have any questions that have not been answered, then you can contact the ticket finder, simply click on the help option on the home page and scroll down to the bottom of the page where you will find all the numbers and contacts of the company.