At first, on the page that should show the products from a category, make the recordset to pick up the category ID (or what ever parameter/variabel you have for the categories) from the link, see what i typed regarding the links at the bottom.
This example is pretty basic.
WHERE catID = colname
If you have different tables for the products and for categories you need to join them so the tables know what to look for and where.
SELCET * FROM tableProducts, tableCategories WHERE tableProducts.catID = tableCategories.catID AND tableCategories.catID = colname
"use INNER JOIN if you need"
Where the colname is the URL parameter you set to pass the parameter in to the page that shows the products from a chosen category.
So when you pick a category, from a menu or link, the link should look something like this: products.php?cat=22, or pass the parameter/varible as text, then i should look like this: products.php?cat=guns.
Hope this helps you out. :)