Julianne,
While awaiting specifics, you might begin at this thread on the
Golden Section & Fibonacci Series in Art, which for now has somehow escaped transfer into this Composition subject area.
Using the "Search Messages" feature, do searches for "golden mean", "golden section", and "golden rectangle", for starters. Mention or discussion tends to crop up in a variety of places. (Don't put those search terms in quotation marks when you enter them.)