Hey and welcome! I had the exact same feelings when I first started and I've only really majored in Frontline modes (Would like to try for Feast with the right people).

The best things to do are to find a class/job you like playing, practicing your rotations(Just like PvE content) and just queuing in! Some modes are a little tricky in Frontlines but if I had to describe them best

Shatter: Def the mode I recommend trying first. This mode has you breaking small formations of ice around the map to get points. At certain timed intervals a VERY LARGE ice spawns, which you and your team want to rush over and do as much damage as possible. The main focus of this mode is to get big ice when it spawns, get your local smalls when they spawn (go into enemy camps if they're busy with something), and staying together as a team.

Secure: This is a mode where you want to capture multiple areas and hold them for as long as possible. In the center at certain intervals nodes spawn, you want to kill these nodes to get a ton of points for your team(like the ice in shatter). Later on in the game a big node spawns which will give the team even more points. The mode relies a lot on communication, knowing when to pick a fight or leave one, and just general cooperation. It gets very hectic capturing bases to have an entire GC alliance come at you guns ablazing.

Seize: This mode is a love/hate relationship. It's basically king of the hill for multiple little nodes that spawn. Your team wants to control it as much as possible (like secure) and defend it from being recaptured. These nodes spawn at absolute random and can either give your team an advantage or hinder them to hell and back. During the match the tomes are ranked B->A->S with them giving more points the higher rank they are. This mode has your team fighting two sided battles all the time so focusing targets and holding your own is a big deal. Tanks and Healers are great in this mode as they can disrupt other people who try to cap the tomes.

All in all PVP is a ton of a fun, I started off as someone who hated it but have grown a big compassion for it and get very excited(lots of yelling) over games both wins and losses.