does anyone know how to add this ad on module

does anyone know how to add this ad on module wen a customer is buying a product I want a thing there that will give them the option to add another product I have inclosed a pic for better understanding
I hope I explained myself ok
here is another website that has the sort of thing I am looking for
http://omnicia.com/zencart/index.php?main_page=product_info&cPath=22&products_id=34

That's in Admin -> Config -> Product Info -> Also Purchased Products Columns per Row

The default setting is 3 columns per row. 0 to turn it off.

Note that this works automatically, so you need to have had at least one order containing multiple products for this to display.

If you want to set it up manually so that you can choose which products are recommended and where, regardless of order history, you want to be looking at the cross-selling mods instead, found in the Free Software Add Ons.