If you are using the default keyboard controls, the pattern should be like this(the image in the first reply is accurate too, but one of the inputs is cut off at the bottom):
C, Insert, V, (PageUp or PageDown + V), (PageUp or PageDown + Insert), (DO, RE, MI, TI, LA,)
C, Insert, V, (PageUp or PageDown + C), X, (DO, RE, MI, SO, FA,)
C, Insert, C. (DO, RE, DO.)
You can also get really carried away with playing the in-game piano:
http://www.youtube.com/watch?v=wXF5M_Yp68I