You will wake up later that evening in your room, with the Headmaster questioning you about what occurred earlier and about Zelda’s attitude some time prior to this. After the scene, open up your cupboard for a Blue Rupee, then leave. The mysterious blue figure from your dream will be near the stairs. Follow her up the stairs and outside.
Continue following the blue figure along the pathway to the Statue of the Goddess and you’ll soon need to drop down to a side area. Follow by going from ledge to ledge, jumping, dashing, climbing, defending yourself, etc., as you need to. Take note of the lower ledge along the way; you’ll find a chest atop it, inside which is a Red Rupee. Continue across the ledges and up the vines.
Eventually, you’ll reach the top area, which is the Statue of the Goddess. Go around the statue to the blue figure and she’ll open a doorway into the statue, then go inside herself. Follow suit.
Statue of the Goddess
Go forward, towards the sword within the pedestal. The mysterious figure from before will introduce herself as Fi, an agent sent by the goddess to aid the hero in his journey. She will ask for you to take the sword. Approach the pedestal and take the sword, following the prompts given, and basically re-do the advertisement commercial for this game.
Afterwards, hold the Goddess Sword straight up, to the sky, and let it charge for your most powerful move at this point, the Skyward Strike. (Note that this creates a mini-projectile that also will hit the enemy, and the projectile goes along the blade of the sword.)
Soon afterwards, you’ll speak with the Headmaster, then Fi again. You’ll receive the Emerald Tablet. This is the key to going to the surface below (yes, there is a surface). Hit the bluish crest in the room with a Skyward Strike to cause the altar beneath it to raise. You’ll then place in the Emerald Tablet and a verdant green ray of light will emanate from the clouds below.
After this, Fi will note that, from now on, she will join you and stay within your Goddess Sword. Press Down to call on her for various info, and do so when locked-on to something for info about it. Much like Navi of Ocarina of Time (in fact, it is worth noting that the fairies of this game went to those nice graphics). Anyhow, leave.