Welcome to FT, mcowpat. I am not certain that I understand your question.

To get frequent flier miles, you must register for one or more frequent flier programs. This does not cost any money. If you have not already registered with the appropriate airlines' programs, do so quickly and you might still have time to submit the boarding passes from your previous flights to get mileage credit.

Please provide us with more information. Which airlines have you used recently? Which airlines do you plan to use in the future?