Any book by her should have the instructions in it if flying geese are used.
I use her flying geese rulers and they come with instructions.
You can do them without the rulers but it is easier with them.
The basic of them is you cut two squares one is 1 1/2 inches bigger than the other. Take the lenght of the goose you want and add 1 1/2 inchs then add another 1 1/2 inches for the second sq. Center the small sq on top of the large one with right sides facing each other. Draw a line just like you do for a HST and sew down each side. Cut on line.
Then you layer right sides facing outer edges matching and draw a line again. Cut. Now you use the ruler to cut out 4 flying geese. They come out perfect.
You have to see it done to really understand and see how simple it is.