I booked online and printed my "passenger receipt and itinerary". When I booked I selected seats for each leg of the trip. My question is, what do I actually bring to the airport? Do I just need a printout of my receipt? Do I need to do the online check-in 24 hours in advance? What about boarding passes? What about the return trip? I guess I'm just thinking of the olden days when I had paper tickets. Could someone walk me through this? It will just be me and my 9yo, so I don't want any extra anxiety!