Research the networks of airlines that are bundled together in a single frequent flyer program. Although each airline has its own program, miles from a variety of different airlines will count towards your mileage credit on a single program. Look for the "Airline Partners" tab on your airline of choice's frequent flyer page.
Choose the airline mileage program for which you want to apply for miles. Pick an airline whose partners you are most likely to use, too.
Register for an account by clicking the "Join Now" or "Apply Now" tab and filling in your personal details.
Click the "Request Mileage Credit" tab or link in the frequent flyer area of the website to apply for retroactive miles from previous flights. Different programs allow you to obtain credit from flights dating back at least six months, and sometimes up to 18 months.
Use your ticket stub to enter the information about your flight, including carrier, flight number, departure date, airports and ticket number. This information is usually also in the confirmation email you receive after booking a ticket online. You can also call the airline with part of the information to obtain the ticket number.
