I haven't played Nintendogs. Is there an in-game keyboard like this:
? I'm not near a piano right now, but I used to play quite a bit as a kid, so I can probably pick out the notes in my head.
EDIT: I've got 20 mins to kill, so here's your first music lesson.
There are eight notes on that keyboard. C, D, E, F, G, A, B, C. The black notes in the middle of white keys are semi-tones -- notes that are in between two different sounds. We call them sharps or flats, but to keep things simple, I'll just give you the sharps. So, the black key in between C and D would be C# (sharp). If I ask you tell tell me what key G# is, you would go to G, then move up to the black key above it. It's that simple.
So, without further ado, here's the keys you'll need to use for HNIC. The rhythm's all up to you!
EDIT 2: Notice how there are 2 Cs on the keyboard -- one on the bottom and one on the top. To make things perfectly clear, I will call the C on the top of the keyboard C2? Got it?
CC FF D#
CC FF D#
GG C2C2 A# G
CCC E C G
CCC E C A G
CCC E G A A# F G G# G D#
GG A#A# B C2