Trouble with setting up pages inside Marketpress

I have a customer who has 3 main general navigational menu items and a lot of sub-menu items (styles) so I created a site that has the three generals as the main nav menus then divided the subs into sub-menus (see http://sunsetsunglasses.com/new). Everything works except I can't figure out how to populate the main menu pages with proper content. I thought about using shortcodes but can't find info about how to create the shortcode with only the info for that menu item (I do not know php/css so the attributes explanations are above my head).

Could someone look at this site and tell me how to easily populate the "general categories", "authentic sunglasses" and "designer inspired" pages with either a dropdown that contains only the associated products or some other solution - other than doing hem one by one?