Adding Custom Field area to 'add new product' page

I am setting up a website to sell ebooks. I want to include the author of each book (product) in the form of meta data so that it will display dynamically on product pages and product lists. The MarketPress page where you enter in the products does not have a custom fields area. How can make this function display, or enter in the author in way that will display dynamically? (dynamically meaning not within the product write-up)

The website is