Shortly after meeting up with Fran and Balthier, Vaan and Penelo run into Ifrit who is guarding a treasure. While Baltheir and Fran are around to help during the fight, they act on their own. You only have to worry about controlling Vaan and Penelo. Since Penelo automatically heals Vaan the only thing to do in this fight is get Vaan close enough to Ifrit to attack him. Once Vaan gets close enough he attacks whatever is in sight and switches targets automatically after he defeats one of Ifrit’s minions. See the video below and if you missed it check out a gameplay video of the first mission.