Tasks are offered in any port from the Town Palace, Tavern, or Church. Depending on what building you select, determines the type of task. Tasks include importing a certain number of a certain type of good, building certain types of buildings, rescuing people or items lost at sea or simply buying goods off a merchant or pirate.
Each task will all carry a time limit and usually the higher the reward the shorter time frame you will have to complete it. Completing 10 is by no means a difficult task and will most likely come naturally as you work towards other achievements and build your gold stockpile.
NOTE: Tasks may not always be available when you enter a port. You may need to back out to the nautical map and wait for the next day to clock over. Also note, you don’t need a ship docked in port, as long as you have at least one building in town you can still accept tasks.