Incorporating HTML

[ignoramus]

I am working with osCommerce. I'm not sure if anyone here is familiar with the system, but I'm hoping this is a general enough question...

here is my page as it looks now:

http://obviate.us/catalog/index.php

On this default index page, you can see it gives instructions on how to edit the text here. but I want to replace this section with an html layout of my product categories.
where among the PHP code would I place this? is it possible to just copy and paste my HTML somewhere? or must I integrate it among the PHP somehow? is there any simple way I can do this??

I'm not familiar with PHP coding at all but i'm trying to change the design without touching it too much...

[Houdini]

Show the code that you have because looking at the source of a page will not revealthe PHP that can generate HTML but not the code that it used to generate such aouput.