Search text box with an image

Hi,
I'm trying to add a search text box with a clickable image inside to my web application with not luck.
Actually, what i want is exactly the textbox this forum has at the top.
Textbox with a text that disappears once the user place the cursor inside, a clickable glass image inside the textbox that will trigger the search functionality (could trigger even a jquery) after clicking.
Any suggestion how can i perform such a thing?
Thanks.