Can we still be a noob at 80? I am a holy priest. I went to Naxx for the first time and used Blizzard's UI. I do not pull out raid frames in groups but individually which ended up making a whole mess on my screen. As a result, I can only healed a few selected people. If that wasn't bad enough wait till I start healing in the Loatheb fight.

Bro, used grid+clique if you haven't already. I was very reluctant to start because I have to relearn my keys. It took me two full days lol. If your mouse does not have enough buttons, use the scroll-over macro keybind.