Tumblr: HTML help, how to put a header image?

[chaaaaa]

My blog theme ; Brand New Day. Please help with HTML ?
Uhh the html for the header bit ish
#header {
position: relative;
text-transform: uppercase;
display: inline;
left: -15px;
top: 30px;
font: 40px Helvetica;
margin: 40px 0px 40px 0px;
padding: 0px 15px 0 15px;
background: {color:Title Background};
color: #000;
height: 50px;
-webkit-border-radius: 5px;
-moz-border-radius: 5px;
}

#header a {
color: {color:Title};
}

#header a:hover {
color: {color:Title Hover};
}

#header h1 {
font-size: 30px;
letter-spacing: -1px;
padding: 0px 0px 0px 0px;
}

#header h1 a {
color: #000;
margin: 0px 0px 0px 0px;
}

#header span {
font-size: 18px;
padding: 0 0 0 15px;
}