image thumbnails in vertical position

How to set the thumbanails in vertical position?

i mean the thumbs 30x30px, when you click on a product image to view larger.

I want to put them in vertical position in the right of the frame in order to gain space in height.

you may view the image to understand what i mean.

I think i have to edit file skins/SKIN/customers/views/product/components/product_images.tpl

but i don’t know what exactly to change

can someone help me please?