Space in listing pages

I just started with my shop and it is far from done.
I would like to have more space between the products in the products listing page.

Have a look at my page. You will see the images are touching each other. I would like to keep the size of them but just generate more space between the products.
Which file do I have to change?

Here is the link: LINK

Thanks for any help

For detailed control of the listing display, add to your stylesheet```
/* space & border between listing items */
.productListing-odd td, .productListing-even td {
text-align: left;
vertical-align: top;
padding: 0.5em;
margin-bottom: 1em;
border-bottom: 3px double #aaccbb;
}

THANKS for your quick reply.
Works great