I just figured it out, myself! I'll try to post here what I did so you can, too
Ok, see this part of your code:
<!-- start header -->
<div id="header">
<h1 id="blog-title">
The Storytellers Spot
</h1>
<p id="description"></p>
</div>
<!-- end header -->
Here is where you put your banner image. Here is what mine looks like:
<!-- start header -->
<div id="header">
<div id="blogtitle"><a href="http://twofor1.blogspot.com/" target="_blank"><img src="http://i48.photobucket.com/albums/f218/mom2twinsplus1/banner-4.jpg"</a></div>
<ItemPage></a></ItemPage>
</h1>
</div>
<!-- end header -->
The font size won't really matter if it's a banner you are making in your scrapping program.
HTH!