Its not true that guilds on Sargeras cant raid wellI dont know about alliance but on horde there is plenty raiding guilds that will help you to gear up and help you to learn everything..Example is my guild named "Endoderm" you are always welcome in guild,nobody will call you a noob because you made a mistake or dont know a tactic on specific boss,our guild master will always explain you what to do no matter what,he is the most patient person i ever seen in this 3 years on molten wow,you can wipe as much as you want he wont disband raid group until boss is down,guild run or PUG? Doesnt matter,he is also patient with PUGs the only thing he doesnt tolerate is going AFK in the middle of the fight while you are dead.
I was noob like you in PVE counting only Cataclysm and this guy helped me alot,i learned everything thanks to him he didnt yelled at me when i make a mistake he will just point to me what mistake i did and my job is to not a fail again on same thing