Looking for alt code to add in for CSS image found in header

[stephenco]

I'm using a free template for my site design and it has the line

#desc {background:#505050 url(images/front.jpg) bottom left repeat-y; clear:both; color:#fff; height:290px; margin:5px 0 15px; padding:0 0 5px 0;}

I want to be able to add the alt tag but can't figure out how to do so?

Can anyone please advise the code?

Thanks, Stephen