flying mounts are very rare
you can get a 7day mount from the world boss dragon drop but that's faction vs faction 100v100 and you're all competing to get the drop for only 1 person/ 200 parcticipants

there are no permanent flying mounts as it kind of makes you avoid pvp....
you can also get a flying mount from in-game events that usually last 1-day or rarely 7days if it's a huge event

other than that there are no other ways and you can't tame mounts which could possibly be flying mounts