Why it is them and not us
The fare decides what a ticket allows, and the airline that issued it is who applies that. Nothing on this site can change a ticket, refund one or reseat you — see Refunds and exchanges for what the fare settles and who settles the rest. What we can do is tell you who to ask.
Where the details are
Every airline in the results has a page of its own, reachable from the airline directory or from the airline's name on a result. It carries where the airline is based, its website, and its phone number.
Two warnings about the number. It is written the way the airline writes it at home, which for almost all of them means no country code — a North American toll-free number dials nothing from Europe, and a number printed without its leading plus is not one you can dial as it stands. And it is plain text rather than a link you can tap, on purpose: a number that cannot be dialled from where you are should not look like one that can.
Some airlines have neither a number nor a website stored. Where that is so, the row simply is not there rather than showing you an empty one.
What else is on the page
Which airports it uses as hubs, the aircraft it flies most, and the other airlines flying from the same airports — useful when you are deciding who to fly with rather than trying to reach somebody.
What to have ready
Your booking reference. It is the one thing that identifies a booking, and it is on the confirmation page and on the booking's own page under My bookings. See Ticket did not arrive for why writing it down matters more here than it would elsewhere.