It sounds like you have two master details page sets that you would like to create. The first is for the category then again for the details of a particular item.
link to productCAT.php with id > link to detail page with product id > details page displays info about the product
The first thing to do is to create a recordset on the productCAT.php page that will select all from your table. Then you need to configure the filter, you will filter on the id column, and then specify the value coming form a URL parameter, then enter the name of your URL parameter that you are using in the links to this page. This is all there is to it, with the recordset being filtered on the id in the url parameter the page will only display info about that category of items.
The details page is the same type of thing. You need to first have a recordset that selects the records from your products table. Then you will need to specify a filter for this recordset as well. Like the previous one it will be filtered on a URL parameter. Just specify the id column, then enter the name of the URL parameter. On your category page you just need to link to the detail page with this parameter and the id in it like this:
details.php?id=<your item id>
When you are crafting the links you can add in the ?id= part then for the value use the binding from the recordset for the id. If you have any further questions about this let us know, it might be best to work on a specific aspect of this first before moving onto the other parts.
