I use the RAWR-Template v0.1.3 using the 'Black' flavor, and to make the change in question open rawr_black_main.css in your favorite text editor and find the following: (note already shows what I changed filename too) ;-)
#header {
color:#f0f0f0;
border:1px solid #ff00ff;
height:120px;
background:url('../images/my_header-bg.jpg') center no-repeat #000000;
margin-bottom:10px;
}
to put the eye in the corner I redid this bit of code:
#header div {
background:url('../images/padlock2a.gif') no-repeat;
height:120px;
}