Put an header image in this code.

Hello Everyone, I’m new to CSS and wordpress, i apologize if this question doesn’t fit the kind of questions allowed.

I was wondering if you guys could help me with this code, I would like to put an image for the header in the background instead of the color.

The website is this: https://www.pagine-verdi.com

The code for the header is:

`#header_outer {
background: none repeat scroll 0 0 #FFFFCC;
}
.logo{padding-top:10px;}
.map_category{opacity:0.9;
filter:alpha(opacity=90);}
#header{ height:100px;
}
#header .header_right {
background: #FFF7EF;
float: right;
width: 386px;
border-color:white;
border-style:solid;
border-width:1px;
border-bottom-right-radius:7px;
-moz-border-radius-bottomright:7px;
border-bottom-left-radius:7px;
-moz-border-radius-bottomleft:7px;
border-top:none;
}

Thank you very very much
Renzo