The Legend of Zelda: The Wind Waker/Dragon Roost Island

The next part of your quest is getting three pearls, and the first is Din's Pearl.

Getting The Sail
You'll wake up on a talking boat, the King of Red Lions. He will tell you how you need to save your sister (and the world), and that you should depart, but he has no sail, and you must get one. Turn left and head up the island. There are a few side-quests you can do here, but if you are just interested in getting the sail, head through the stone arches by the docks at the opposite side. Follow the road until you see a man in a parka behind a counter. If you have 80 rupees, talk to him and buy what he sells. If not, head back on the wall behind the man and you'll find a little dock area. Break the pots for some rupees, and if that still isn't enough, go around slashing bushes around the island. When you get 80, buy what he sells - the sail.

Equip it and head back to the King of Red Lions. He will explain how to sail, so do so, and head to the next island, Dragon Roost Island. Follow the wind towards the large pillar-shaped island on the horizon. Occasionally you may find some rupees atop barrels, but it is mostly a boring, straight ride to Dragon Roost.

Dragon Roost Island
When you arrive, KoRL will teach you how to use the Wind Waker, a magical conductor, much like the Ocarina from Ocarina of Time. Head left and you'll see some blue bomb flowers. Use them to blow up the rocks that block your path. When you reach the top, you'll have to sidle the wall to get across the broken bridge. Drop one more bomb flower and continue on. You'll meet up again with Quill. He'll invite you to enter the island, so do.

The Rito tribe will tell you of their problem with their wing-giving dragon, Valoo, and that he has become violent and angry. They ask you to help Prince Komali, the chieftain's son. Quill will give you a Delivery Bag, for holding letters.

Take Quill's advice and look for Medli in one of the upper rooms. She'll give you a letter to Komali and she'll also ask you to meet her later. It's not a date. I promise. Head down to the bottom floor and enter the door that doesn't make you leave the area unless you go through an actual door.

In this room, Prince Komali will be sitting in bed holding Din's Pearl, the thing you're after, but you can't get it yet because he won't give it to you. Instead of stealing it from him, leave his room and, in the main room, go through the door with the feathers above it.

Out here, jump down to find Medli. She'll talk to you, and then ask you to throw her up onto a ledge. Pick her up and go to the top of the little hill thing. When the wind blows towards the ledge, throw her towards it and she'll fly up there. She'll give you a bottle for your efforts.

Leave this area and head down to the ocean. Equip your bottle and grab some water with it. Head back up to the entrance to Dragon Roost Cavern and pour the water on the red withered bomb flowers to turn it into one you can use, then throw one down onto the rock below. This will create a lake so that you can swim and follow Medli into Dragon Roost Cavern. Throw bomb flowers into the pots that the statues hold, and they will fall over and make platforms that allow you to cross the lava. The next area is your first sword-equipped dungeon: Dragon Roost Cavern.