sorted the problem.
http://www.actionfigures4u.com/index.php?main_page=index&cPath=1_67
here's the easy way and i DO feel dumb at this point.
you can't change your catagory image picture to a banner because if you do it changes all of those images to banners and you only want to change the image that appears at the top of the page.
create your banner image and save it into images (or where you prefer).
now simply go into admin, catalog, catogries/products..............and click on your catagory. from this new list click on the green action button on the right of the page with the letter 'e' on it.
now............you need to simply upload your image, but instead of where it is telling you to upload it at the bottom instead upload it into the text area.
you now have to disable the cataogry image that zen cart uses, the one that you still see at the bottom of this page, utherwise you will have 2 images.
admin, configuration, product listing..................at the bottom (about 3 up from the very bottom) click on 'include product listing sub catagories image' and set this to false.
done.
i thought there would have been an easier way with a line of code redirecting an image path but nobody seems to know, if you do please let me know as its a lot of images all the while.
cheers.
andy.