Lower opacity on an image hover

Hi Ari,

My website is: http://kitchenworktops.ie/
The images I would like to fade on hover are the three linked images just below the main slider on the home page. (1) Granite Worktops (2) Quartz Worktops (3) Marble Worktops.
Also, I couldn't see a reply option to reply to your last message...
Is there an easy way to reply each time? Thanks. Glen.