I have a Feudog D that came with book and cd. Really like it. However, to play some of the songs I enjoy, I recently bought Clarke C. I know the most basic of fingerings but would like a chart for a C. That or have some one explain how to read the other chart I saw in the Key link.
Thanks 
The pattern of fingerings in the same for a C whistle as for a D whistle. The only difference is that the note will be one whole tone lower on the C than on the D, and it will play a C major scale rather than a D major one.
So working from the bottom up, a D whistle plays D, E, F#, G, A, B, C#, D and a C whistle will play C, D, E, F, G, A, B, C.
You can either play the tunes you know using the same fingering, in which case they will come out a whole tone lower in C major or start on the real note, which will require some half holing/cross fingering for accidentals if the piece is in D. If it’s in C to begin with then you won’t have to worry.
You should post to the whistle board.
Also, you should do a search. This question has been asked and explained many times.
Essentially: a whistle is a transposing instrument. That means, all whistle music is written in D (as if the whistle was a D whistle, really.) and you pick which whistle is appropriate for the key being played.
Thanks for the help, and corrections. New to flutes and essentially music. Trying to learn about music by learning the flute. Thanks again.
Warren