[quote name='iamapirate' post='579631' date='Aug 24 2009, 10:17 PM']well, if you start on C, then you're playing in F I think. It definitely doesn't start on the root note, though![/quote]
If the song is in C, the first sung melody note will be G, a 5th above.
Simple chord progression is
C, G, G, C, C, F, C, G, C
This is in the key of C