yes you need to edit things in the index.php of your theme.
There's many ways doing this and I'm gonna post a simple but different solution:
Your index.php of your template should look like this:
<!doctype html>
<html lang='{{site_lang}}'>
<head>
<meta charset='utf-8'>
<title><last:ndxz_title /> : {{obj_name}}</title>
<last:page:meta />
<link rel='alternate' type='application/rss+xml' title='RSS' href='{{baseurl}}/xml/' />
<link rel='stylesheet' href='{{baseurl}}/ndxzsite/{{obj_theme}}/reset.css<last:page:version: />' type='text/css' />
<link rel='stylesheet' href='{{baseurl}}/ndxzsite/{{obj_theme}}/base.css<last:page:version: />' type='text/css' />
<link rel='stylesheet' href='{{baseurl}}/ndxzsite/{{obj_theme}}/style.css<last:page:version />' type='text/css' />
<last:page:css />
<last:page:javascript />
<last:page:onready /><plugin:backgrounder />
</head>
<body class='{{object}} section-{{section_id}} exhibit-{{id}} format-{{format}}'>
<div class='top'>{{obj_itop}}</div>
<div id='index'>
<div class='container'>
<plugin:index:load_index />
<div class='bot'>{{obj_ibot}}</div>
<last:page:append_index />
</div>
</div>
<div id='exhibit'>
<div class='container'>
<div class='top'><!-- --></div>
<!-- text and image -->
<plugin:page:exhibit />
<!-- end text and image -->
</div>
</div>
<plugin:page:append_page />
<plugin:page:closing />
</body>
</html>
Now your Pre-nav area is your header area.
You need to define how it's going to look like by adding a css rule to your style.css, for example:
.top {
background: yellow;
height: 50px;
position: relative;
width: 100%;
}
Of course in the pre-nav area you can insert an image, an h1 tag, text or even a combination of all of the above.
Try it.