If you sail to Gale Isle, you will quite soon notice that you can't land for now, and Fishman will suggest you head five times south and once east, to E6. If you decide to go to E6, he will tell you that the required item is in B2. The same way, if you head for Headstone Island, you can't really do much there. Fishman will advise you head for the Fire Mountain, which can only be reached with the item in B2. Therefore, let's head for B2, where are located the Mother and Child Isles.
Mother and Child Isles
It seems you cannot reach Mother and Child Isles from the sea. If you look for Fishman, he will show you a nearby tornado. Head for the tornado, then as soon as you notice Cyclos on his cloud, draw your bow and shoot three arrows straight at him. He will then teach you the Ballad of Gales, which will allow you to travel from point to point between nine given locations in no time. Therefore, play this ballad and head for the Mother and Child Isles, the place where you actually are. The tornado will bring you to the top of the Island. Here you will meet the Queen of the Fairies, who will grant you both the power of Fire Arrows and Ice Arrows. Play the ballad once more and choose E4. From here, sail north-east to reach the Fire Mountain.
Get quite close to the mountain, then shoot an Ice Arrow at the summit. You will now have five minutes to get inside the mountain and find its treasure. Land on the island and climb the mountain while constantly going right. Get past another ledge before reaching the top and jump in. Jump on the platforms on the left, while avoiding or getting rid of the Keeses, then strike the two caterpillars with your sword, or with your Skull Hammer when they curl up in balls. Open the chest that just appeared and pick up the Power Bracelets. Then lift and throw the stone head to go through the passage leading to the exit.
You can now head back to Headstone Island.
Upon arriving, from the southern side, lift the stone head and get in. Get close to the stele and take out your Wind Waker to play the tune. You just learned the Earth God's Lyric. At the same time, the ghost form of Laruto, Zora descendant and former Sage of Earth, will appear before you and request you to find a harp player who will be able to open the door along with you. Get out and play the Ballad of Gales to get back on Dragon Roost Island, the harp player being Medli.
Dragon Roost Island
Head for the village, go to the second floor and exit from the second door. Then go right, use the Grappling Hook to swing across the gap and go forward until you reach the end of the path. Talk to Medli and play the Earth God's Lyric right in front of her. Upon passing out, Laruto will grant her the right to inherit her position as the Earth Temple's Sage.