How to change "Add to cart" buttons to static images

[noesac]

I want to embed (flatten) the text "Add to cart" into the button image, and remove the floating text...if that makes any sense.

In homefeatured.tpl, I have changed:

{l s='Add to cart' mod='homefeatured'}

To:

{l s='' mod='homefeatured'}

In the above change I removed all instances of "Add to cart".

Now I've created a new button with "Add to cart" on it, how do I change the default image?