You're almost an adult now, so you should power up with some new tools. At an island at the Back of Zora's Fountian there's a dark gray boulder. Blow it up.  Now enter the giant crevice in the wall.  You'll recieve Farore's Wind from a fairy. 

Although it's really pretty useless its kind of cool.  After getting Farore's Wind you need to head for Hyrule Castle.  You'll see zelda fleeing from Ganondorf.  After the scene is over dive in the moat for the Ocarina of Time.  Zelda will then teach you the Song of Time, which is really cool.  After that walk into town and enter the castle area.  Climb the vines on the wall and go over to the arch.  Fall off it and head for the 'Dead End', according to the sign, that is.  Blow open the passage here to recieve Din's Fire, a gift from a faire.  Ready for adulthood?  If so head to the Temple of Time to wield the Master Sword.  Be prepared for some suprises when you're about to pull the Sword of Evil's Bane from it pedistal.