Frost is NOT a viable spec for raiding. Frost is for PvP. You'll want to go arcane, then switch to fire once you have the gear for it---and you'll need really great gear for fire. You can always armory me to check out a cookie-cutter arcane talent tree. My mage is Snowmiser from Aerie Peak.
Arcane is easy....basically Arcane Blastx4, then arcane missles when missle barrage procs. Sometimes I'll cast arcane blast 5 or 6 times just to get missle barrage to proc....but it usually procs before I stack arcane blast 4 times. For AoE, simply use blizzard.
