Har! It's a Pirate's life fer ye! Navy work is all well and good but Pillaging will really bring home the booty!
Pillaging is when ye sets sail with a Crew o' real Pirates and take on the scurvy brigands that ye might find at sea. Successful sea battles brings in a haul o' cash!
Open up the Noticeboard and select the Pillaging tab.
Taking a Pillaging Job from the Noticeboard
Officers of Crews can post vacant positions on the noticeboard as they sail, so that young Pirates arriving in port can apply for work on the ocean wave. Ye can examine the crew info before you sail, to see what sort of folks they are and how the booty gets divided. This information is also included in the job description, along with the pay rate and the type of vessel.
Once you've selected a ship to job with, click/tap on apply and wait a few moments, while the Officer has a chance to review your request (she will probably be busy puzzling at the time).
Should you be successful the Officer will /job you and invite you onboard the vessel. Accept and you will be whisked out to them.
The mechanics of Pillaging are discussed in the Sea Battles section. Be sure to follow the instructions of yer crewmates and the officers in charge, lest ye be forced to walk the plank!