you are still a composer writing a new song
and the new song is in the key of D (2 sharps).
In the melody line, you find that one of
the notes that is normally played as a sharp
needs to be played as a non-sharp. To do
this, you would label it with a "Natural"
note sign. Look at the figure above.
See the C ? The key signature says to sharp
all C's. See the little parallelogram to
the left of the C note? This is a