Automate creating .csv

The attached sample spreadsheet is what I use to print a catalog. I want to use this data to create a .csv file that I can use to create a menu system for our website. For example, "Screw Hardware" is a main category, with "Generic" being a sub-category of "Screw Hardware", etc. Obviously, I want columns A, B, C to contain the category names for each product listed under them.

TIA

Rich