Dragon Roost Island
This island is inhabited by the Rito tribe, winged people who are in charge of the mail delivery, and Valoo is both their guardian and the "Sky Spirit". As soon as you land on the island, the King of Red Lions will give you the Wind Waker and teach you how to use it. Follow his advices to play a tune in 3/4 time and 4/4 time.
Go straight ahead under a rock arch and swim to the small island. Take a look at the stele, use the Wind Waker and play the notes to learn the Wind's Requiem. As soon as you finish playing it, Zephos, the Wind God, will appear and tell you about his angry brother: Cyclos. Go back to the main island. If you can talk with Tingle, make him drop a Bomb on the big rock and jump in the hole. Fight the enemies in the various rooms until the white door unlocks. Open it and you will find a purple rupee in the chest.
Go back under the rock arch, and head for the small pond. Lift a Bomb Flower and throw it at the big boulder. Go ahead on the path and throw another Bomb Flower at the rock on the right. Follow the path, then pick up the Bomb Flower at the end, go left and throw the Bomb Flower at the further rock. Get on higher grounds, go past the ledge, pick up the five rupees and jump. Throw a Bomb Flower at the rock and go ahead until you meet Quill, the mailman. Go on ahead and you'll get to their "village". Inside, their Chieftain will tell you about the dragon Valoo and the Rito's customs. Agree to help Komali and meet Medli. Quill will then give you the Delivery Bag.
Now, go on the path leading to the second floor. Get in the first room, talk to Medli who will give you the Father's Letter and put it in your bag. Go back down and follow the only corridor that doesn't lead outside. Get into Komali's room, talk to him, give him the Father's Letter and talk to him once more. Go out and follow the passageway to the left. Go left, jump to find Medli and agree to help her reach the summit of the mountain. Carry her and climb on the platform behind you. When the wind is blowing in the right direction (in front of you), take some momentum and throw her ahead. Upon reaching the ledge, she will offer you a Bottle. Go near the big rock and pour some water inside your bottle. Climb the wall behind you, and pour the water on the red dried flowers. Take a Bomb Flower, throw it at the rock in the middle of the room to blow it up (get the timing right or it will fall into the water) and swim to the other side. Get another Bomb Flower and toss it into the right pot, then do the same with the left pot (you can use the first fallen statue). Climb on the fallen statues and walk down the passage.