Great question!
Usually what would happen is that PCs would develop story macguffins (like a treasure map) either through chargen or through their story arcs (the natural course of the personal plot they're pursuing, whether the items were given by staff addressing the story arc, or through interaction with another PC). And then, after developing this impetus, the player could opt to further the plot by making a "dungeon" area to explore.
Sometimes people bake a macguffin into their character concept, like we were suggesting that players have an idea for why their character is on the ship. So, in that case, maybe you could have proposed in character generation that your character already had a treasure map, and had gotten onto the ship to see if she could get closer to a tiny rocky island that was supposedly off the north coast near Al-Sabiyyah, that was supposedly where this treasure was buried.
And then on the ship, Eleni could socialize with other PCs and try to recruit them to her adventurous endeavor. Once you had enough Presence to build a "dungeon", you could build this little island, and submit it for approval. And if it was approved, you could have Eleni take her little group of PCs and go explore the island. If it wasn't approved and the ship ended up sailing past where the island was supposed to be, Eleni would probably sigh and say, "Aw. I guess the treasure map was a lie, and someone cheated me in the bazaar!"
That's basically how things would work going straight from character generation.
But while we're totally here for people who have advanced concepts like that from the get-go, we also understand that many players (like myself) really have no idea what to expect when starting to play a game, and prefer to make an open-ended concept in order to go with the flow. In that case, what you'd do is make a story arc.
Nothing specific like "I found a map (because there is no map)" or "A sailor told me that an island was there (unless a sailor did actually tell Eleni that an island was there)", but something more like "Eleni thirsts for adventure! She's keeping an eye out for any and all opportunities!" and then you'd document all Eleni's attempts to stir up news of a possible adventure, like probably she asks other PCs what they're doing, inquires if anyone's heard of any buried treasure around Al-Sabiyyah, et cetera. Maybe you read the wiki and find something in the lore that you think Eleni could be particularly inquiring about, and roleplay doing that for a while.
Eventually, staff would address your story arc. All character story arcs show up in the admin panel, ordered based on how much Presence has been invested into them. We address the arcs from the top down. We'd see "Eleni is thirsting after adventure" and check through the recorded developments you wrote to decide how best to provide Eleni with some interesting hooks to follow (or maybe, she's already rustled up a pile of her own hooks from her efforts, and just needs some help with achieving related goals). Maybe we'd animate a sailor who sells her a treasure map! (And now you're at the part in the story where you go forward from possessing a treasure map.)
Hopefully that makes things a bit more clear! If you or anyone has more questions about this system, please ask.
Added note: a "dungeon" is absolutely not necessary for pursuing a plot! There are many existing areas, even on the ship itself right now, for adventurers to explore. It's just relevant to the idea of players running plots themselves, sometimes, if the area that players want to explore is not yet built. However, I wanted to add this note to explain that there are actually things to explore and adventures to have on the ship right now. Engage with the world and you'll see them!
