i deleted the previous post since it dealt with dynamic images rather than having images assigned to options
but to do what the link you posted showed...
in the for loop (assuming you have your options set up as radios) inside the customer_options.tpl page you would put
the image tag before/after the corresponding radio button
but you must have a naming scheme to do this
ie:
{foreach blahblahblah}
<input type="radio" blahblahblah><img src="{thesmartyvarfortheponame}-{thesmartyvarfortheoptionid}.jpg">
{/foreach}
if you just want to click on the fabric without the radios, then you do something similar
but now you would include a hidden input (this will be passed onto the add product function) and set the onclick of the image to a javascript script that changes the value of the hidden input...at least thats how i would approach it
...im not going to go in too much detail since the mod i am working on to sell incorporates this as well as many other things for product options