Sounds like U didnt care about preparing at all tbh.
There's a PvP section in Ur main menue, which U had have found by scrolling. Like all other menues U should scroll thru when starting any newish games.
As well there are many NPCs at Wolf's Den who introduce U to each PvP mode with some overall information.

Be ware that anything in FF14 has any NPC or some pop ups for information.


Sounds awful but it's kinda hard learning ^^