hey I'm newb to WoW, and I'm looking for a good TBC mage build to get me started. I realize there's other posts concerning what I'm asking, but I basically need the step-by-step.

what is your play style, ya i know your new to the game but do you want to level faster or do you want to do all the quests and get to know the game inside and out?

Fire = hits the hardest and kills mobs fastest. BUT you will burn through mana like none other.
Frost = survivability and you use less mana but doesn't hit as hard as fire
Arcane = i would pick this a bit later down the road, it's not new person friendly

Your first 5 points are pretty easy they go into either improved fireball or improved frostbolt.

but here is a good post to read that has walk through builds

http://forums.wow-europe.com/thread.html?topicId=173227419&sid=1