How to replace text with image?

[pattyo1]

Hello guys, My website is http://sunnyroad.sk. Im trying to replace text "Vypredané" with image. 

This is how it looks like 

 

And i want something like this 

 

I guess this is the code 

	{if isset($product.on_sale) && $product.on_sale && isset($product.show_price) && $product.show_price && !$PS_CATALOG_MODE}
									<a class="sale-box" href="{$product.link|escape:'html':'UTF-8'}">
										<span class="sale-label">{l s='Vypredané' mod='labhomefeatured'}</span>
									</a>
								{/if}

I dont know if it is even possible but i really appreciate any suggestion. Thank you 

Edited April 12, 2016 by pattyo1 (see edit history)