Category Images in tpl_top_nav.php

I have my main category images on my index page in a row, (6 images), but I really want these permanently in my header (tpl_top_nav.php file), so they are at the top of every page - but I need to find the display code which shows the categories so hopefully I can just copy and paste it.

Does anyone know what file this is in, or if I would have any issues doing this?

Regards

David

There is no such file as tpl_top_nav.php in standard Zen Cart, so you have some customized template and we can't know how its files are configured.
The code involved wouldn't be just a single chunk; there are parts of it in several files, mainly /includes/modules/category_row.php, with supporting code in others, and something like a categories class that gives the underlying info.