The combat in Pirate101 it's very different from the Wizard101 combat system, but don't worry, after 2 or 3 combats you will start making you own strategies.
In the beggining of the combat, a chess like board appears and it shows many squares and symbols representing you character, you companion(s) and you enemies, starting from there you choose where do you want you or your companions to go, what enemie to attack and what powers to use, it's not that difficult, it appears like this one:
When you decide what you and you companions will do, click Done and let the action begin! The chess like board will disappear and you will se your characters move and attack you enemies with cool and powerfull attacks.
You'll also have in every battle at the right corner in the top when you are planning your strategie victory conditions, some will say to you defeat all enemies, defeat the king, protect someone or even interact with objects, do them and you will not regreat.