Lake Hylia
East of Lake Hylia (according to the map), you can find a field with two scarecrows. Speak with the scarecrow Bonooru (the one closest to the lake), then take out your ocarina and play something for him. You need to play an 8-note song, play it quickly and write it down so you can remember it easily!
Now that you've gathered the three spiritual stones, you can go meet Zelda in Hyrule Castle, but take advantage of this moment to collect as many items as possible, such as Pieces of Heart, Gold Skulltula Tokens that you couldn't get without the Boomerang, thus getting the Adult's Wallet, the Stone of Agony, the Giant's Wallet and even Bombchus! You can also buy and plant Magic Beans. Then, head to Hyrule Castle. If you are in Lake Hylia, talk to the Owl so he takes you there.
Hyrule Field
As soon as you get close to the castle, you will witness Impa and Princess Zelda escaping, then you will meet the evil Ganondorf.
As soon as he leaves, jump into the moat and dive to grab the Ocarina of Time. Using telepathy, Zelda will teach you the Song of Time. Go to the Market and climb the stairs at the back on Link's right side.
Temple of Time
Get in and walk to the altar to place the three Spiritual Stones. Then play the Song of Time and the door of time will open. Get in and grab the Master Sword.
You then wake up 7 years later inside the Chamber of Sages within the Temple of Light. The Sage Rauru will explain you what happened, especially that Ganondorf was able to steal the Triforce and enter the Sacred Realm. The sage then entrusts you with the Light Medallion and asks you to find the other sages. Then you meet the mysterious Sheik who will help you with your quest. Following his advices, get out and go to Kakariko Village. If you have at least 70 rupees, you can now go to the Lon Lon Ranch to win the horse Epona.