Add image banner in header

Quote wpmaster:

Hi,

I created a simple wp theme, only with menu navigation at the top.
Then I set the top margin to 25 px, so that I can have big space to insert an image banner.
But in Artisteer software, we can't insert just the banner on top of the menu, but when I look at the header.php source code, there is no place for me to place this image banner.

The following screenshot describe what I mean:

<a href="http://imageshack.us"><img src="http://img218.imageshack.us/img218/2574/52163722.jpg" border="0" alt="Image Hosted by ImageShack.us"/></a><br/><a href="http://g.imageshack.us/img218/52163722.jpg/1/"><img src="http://img218.imageshack.us/img218/52163722.jpg/1/w320.png" border="0"></a>

The red color box is the image banner that I want to put in.
Anyone know how to add the image banner into the header that I described above?

Thanks in advance!