When engaged in battle, the "Attack" button changes to the "Target Switch" button. That is a pretty self explanatory command. Under that is your magic list. Selecting it will provide a full list of magic. If you highlight it and press right on the control pad you get 3 more options: "White Magic", "Black Magic", and "Songs". These act as a filter and only provide a list of those types of spells or songs. Simply select the spell or song and choose a target to cast.
When casting spells, always remember about the casting time. When you are trying to cast a spell, moving your character or getting attacked will cancel the spell. The time that it takes to cast a spell will appear on top left side of the screen. Basically, casting time will shorten as your magic level goes up. When casting spells, you have to get somewhat close to the target. The distance varies with the spells.
The third option is "Ability". Selecting this will bring up a sub-menu with 4 options: "Job Ability", "Weapon Skill", "Ranged Attack", and "Pet Command". "Job Ability" shows a list of your job class abilities and their recharge times. "Weapon Skill" shows a list of your current weapon skills. "Ranged Attack" uses your current ranged weapon to attack the enemy. "Pet Command" is for beastmasters who can tame monsters.
The fourth option is "Item". Selecting it will provide a list of all usable items. Using an item takes preparation time also. The preparation time will vary depending on the item and your job level. Actually, I rarely see items used in battles.
The fifth option is "Cancel Attack". When "Cancel Attack" is selected, you will put your weapon away and disengage. If you highlight it and press right on the directional pad, the command "Help" will appear. Select this command when you want someone near you who is not in your party to help. You will not gain any experience if you use the help command.
When you want to flee from the enemy, de-activate the target lock, and run away from the enemy. When you are in battle, target lock will activate automatically. You can de-activate the target lock by pressing L3 button or the [*] key on the keyboard. Your character will move slowly if you do not de-activate the target lock.
The sixth option is "Determine". Use the "Determine" command when fighting a new monster that you've never seen before. The "Determine" command tells you if the monster is practice [very easy], easy, same level, higher level, strong, very strong, or very very strong. The same monster may have different stats in different areas, so you should use "Determine" to be better prepared.
For a list of all the low level magic and weapon skills, click the links on the left margin.
