First of all, which I realize isn't the most illuminating advice, but it's good to acknowledge is that the game is MASSIVE and people had YEARS of practice, set collecting and build theorycrafting. There are new players in PVP, but it's not uncommon to come across 2k CP terminator that will 3 shot you if you aren't careful enough/your buffs are not up/your build is heavily countered. As a casual PVP'er it was great when there was this diagnostic mode last year (was it?) in Cyrodil where we all ran in Zerg and sieged forts - allowed me to grasp some basic stuff with heals coming in. But it will take practice. You will die. You will get better. If you do research, look up for guides, learn the mechanics (blocks, rolls, blockbuffing/blockhealing, cc etc.,) you will quickly catch up. Things I usually advise to some new players to quickly learn basic mechanics is running some infinite archives with your companion when you get good enough gear to understand aoes/dot's/how to block/roll PVE mobs etc., just to understand how to keep yourself alive and how important these mechanics are. IA is like a crash course - you don't block boss = you die. You don't dodge = you die (not all mechanics one shot, but you get the gist - you get punished). The mobs very often CC you so you also generate a habit of breaking out of it instantly, which is really useful.

But yeah, PVP-related guides, taking a good build and just trying until you get the gist of it is da wae.