I just started playing again and got the level 90 boost when preordering WOD.
A feral Druid was my final decision and now I don't have any idea how to use the rotation.
I play almost only PvP. Can you guys help me out how my rotation should look like?
I wouldn't bother with Thrash unless you really really need the Physical Damage debuff on a melee class, and definitely wouldn't recommend messing with it as a new feral player. Just remember this general priority for damage and you're good to go:
Savage Roar > Rip > Rake > Faerie Fire > Shred > Mangle
Faerie Fire won't affect the damage of your Rip and Rake since bleeds ignore armor, however you do want to get it up as soon as possible. Vs rogues (and most druids) it should be your first global. (debatable if they're stunned, but if a rogue feels they can kill you in a dance when you're at low gear they might trinket and vanish instantly)
Don't waste too much energy on Ferocious Bite until you're more used to how much energy you're spending, how much you're taking in, how well you can track your bleeds, how tanky some classes are, ect.