Read one of the many existing Fire Mage guides and start practicing the "rotation" as much as you can with the skills you have. You're on level 37, so don't expect to be doing much at this point. Plan on playing any PvP? If so, level as frost (I would level as frost regardless, but that's your call) and start practicing kiting. It will help down the road.
I would seriously recommend going Arcane. It is so much better at low levels, and at 85 fire just can't compete with it. Fire is best at the higher ilvls.