but that is not what you are asking about, you are asking about adding an Add to cart from recordset button, and why it only adds the first item.
My reference to your catalog is not terms of how you are entering it, but rather how you are displaying it.
when using a database driven catalog, you generally have a a search page, a results page that displays a collection of records from your products table and detail page that displays a singlle product.
you can add the eCart add to cart button to the results page or the detail page.
you can create these pages manually in Dreamweaver, or you can use DataAssist to create them.
for details on creating this in Dreamweaver see the following pages from the DW Help: