Contract 01: 01 Eye For An Eye

Once you accept the contract, open your map. You'll see a large, green investigation zone to the southwest of Castillo de Jagua. Sail your ship towards this area.

As you get closer, use your spyglass to scan the waters and identify the target ship. I found it around coordinates 255, 425. Keep an eye out for a large frigate – this will be the San Lorenzo.

Don't worry about the San Lorenzo becoming hostile just yet. You can sail right up to it. Take this opportunity to get close and unload some serious damage using your heavy shot and broadsides.

Continue to hammer away at its health until it's weakened enough to board. While you're doing this, make sure to also take out the gunboat that's escorting the San Lorenzo, if you haven't already destroyed it.

Once the San Lorenzo is sufficiently damaged and incapacitated, approach it to initiate a boarding sequence.

During the boarding action, your objective is to defeat 15 of the enemy crew members and destroy 2 powder stores located on the deck. Successfully doing this will complete the contract.