New EU spineshatter player and first time WoW player

Hello, first time ever playing WoW, I joined Spineshatter EU and went undead warlock, I am at level 16 and was wondering if thus far I had made the right choice with my class choice.

I want to do dungeons soon (eventually) but I have no idea on what would be an ideal prep/where to look to join them. I have been following some guides on specs and upgraded my gear along.

How welcoming is this game to very noob players in term of game background?