Actually you can play traditional sheet music on a Native American flute (if the song is limited to one octave).

If there are two or three notes outside the octave range; you can hit those notes by playing the note in the octave the flute can play; but over blow the note to make the flute jump up an octave.

I would recommend for you to get a small booklet "Introduction To The Native Flute.

You may be able to buy it from High Spirits Flutes www.highspirits.com , and I have seen that booklet sold on eBay a few times. This booklet teaches proper care of the wood flute, and has complete finger charts for the five hole flutes, and the 6 hole flutes.