Carol -
Here is a tutorial on a pinwheel whack and stack using a 45 degree triangle. It does not do a good job of showing the layout and cutting but it does a good job of showing how it goes together.
http://www.bobrow.net/kimberly/Quilts/Tutorial
If you use a 45 degree triangle you will need 8 complete repeats of your pattern because 8 * 45 = 360.
This is different from the one I did. I used a 60 degree equilateral triangle and ended up with hexagon pieces (6* 60 = 360). I had purchased a very expensive piece of fabric and wanted to play. So, I made this for a demo piece for the shop I worked in and did it from a Batik which is not a precise as a print so not as good. but I included a pic of the final product.
I have not yet to cut into my other fabric as I have been "chicken".
Good luck :?