thumb images

[Bit Stupid]

Hi all again

I have been having a bum time trying to figure out images in Virtuemart.  I have been reading and trying endless posts about creating a new file inside the template/html folder and copying the default.php files etc and adding code such as
echo $this->category->images[0]->file_url_thumb;
or
echo $category->images[0]->displayMediaThumb("",true); ?>
or
another 3 line piece of code (sorry cant copy it here lost the url and cant find it again).  Here is my story:

1 - on the category product overview page I want to display a product Thumb image (I have all my images uploaded through CSVI - downloaded to server from external url and thumbs already created). No matter what I try I cannot get them appearing.
I have tried to use this previous post by edvc http://forum.virtuemart.net/index.php?topic=97744.0;prev_next=next#new (half way down page 7). As this seemed to work a treat I amended line 252 with the below in the thought my hard-core noob attempts might magically create what I need!  Suffice it to say nothing happened!
Can anyone help with anything that will add thumbnail images to the category product overview pages? VM 2.0 Joom 2.5 JAT3 Purity_ii template.

2 - on the product details page I seem to be displaying a thumbnail sized pic rather than a full-size image. When I click on it it is the full image.  How can I display the full image here instead?  All my images are already a standard 450 px in height.

Thanks sorry site is localhost st moment for development so screenshots attached.

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