Add product offers selected products

[beed]

Hi,

i would like some help adding product offer text for certain products, to display next to product the text "offer" this will be displayed next the "available" text, and how i would go about doing this. Which files i will need to edit, I have edited the product-list.tpl, and inserted a new span class, however this display the text "offer" next to all of the products listed and not just the products i want to show which i expected, as i need to specify. If someone could point me in the right direction as i think that i am using an incorrect method. I have attached a screenshot which details this.

thanks very much.