
After talking to Malon in Hyrule Market, head north towards the castle (between the archery and mask shop) and wait there for it to turn night. Then go back into Hyrule Market, and straight back out again, you should see Malon standing against the right hand wall near some vines. Talk to her and she'll tell you how her Dad, Talon, has gone missing, and then give you a Wierd Egg on the condition you look for her father. Set it to one of the C buttons as soon as you get it, if you don't do this, the egg will not incubate and hatch.
Climb the vines, and walk along this ridge until you come to the top of the castle gates. Just walk forward and jump off, if you keep your eye on the hill to your left, you will see two major 'bends' in the 3D rendering of the hill.
Walk up the hill just before the second kink, but not following it, start just before it, and end past it, far enough away from the guards standing on the path. Now if you make your way roughly straight towards the stairs ahead of you, you will notice a wall on the far side of the stairs, walk towards that wall, the 'bricked' section of the wall is climbable. Climb up and walk straight forward. Swim down the moat and on your right as the moat bends, you will notice a sort of embankment, walk up it and climb onto the path.
Hopefully by now your chicken should have hatched, if not wait until it does. (You can speed up this process if you have been to Kakariko Village and learnt the Sun Song) Once your chicken has hatched, walk to Talon, and use the chicken to wake him up.
He'll tell you how he managed to fall asleep and then runs off once hearing that Malon is looking for him. There are two crates in the vicinity, pull/push them off the edge of the path into the moat, (one on top of the other) and you should hear a chime to tell you it's done. Climb up on top of the box and jump across to the small drain hole.
Before you go in, you can only do this part during the day. There are extra guards posted at night and you can't get past them. Crawl through the hole and once you are through, you will appear in the courtyard of the castle.
Walk through to the next section and you will be confronted with a series
(about 4) of rooms with guards walking in circles. Your best bet to get through this is
to just wait patiently for a little and get used to the movement of the guards. You should
be able to get through reasonably easy, but if by chance you do get caught, you'll just
end up near the crates.
Once through, you will end up in the final room, with Zelda standing
straight across the area from you. Just walk straight up to her and speak to her.
She will tell you about some of the legend of Hyrule and about the Triforce, as well as some
stuff about a prophetic (or is that pathetic? ;) ) dream she had, she will also ask you
to peek through the window at the guy she was staring at, look and you will see Ganondorf.
Anyway, once she's finished, walk back to where you came from and you will
meet Impa, the Princess' attendant. She will teach you Zelda's Lullaby and then lead
you out of the castle. She'll then tell you about where the second spiritual stone is located
and also to come back to the castle after collecting all three stones.
Next destination, Death Mountain!
