Lucerne, I checked the CP and those stripes are actually not exactly sixths, but there is a very easy way to get them:
First fold the red line (diagonal).
Then fold the short edge to this red line to give you the blue line as angle bisector.
And from the end point of the blue line you get the vertical green line.
Repeat this for the remaining three smaller stripes to get all the horizontal lines and then you can fill in the remaining creases easily.