So you want one banner in the header instead of a banner and the "top module empty" one?

In ....templates/rhuk_solarflare_ii/index.php file, find and delete; 

<div id="top_inner">
     <?php
        if ( mosCountModules( 'top' ) ) {
         mosLoadModules ( 'top', -2 );
        } else {
         ?>
         <span class="error">Top Module Empty</span>
         <?php
        }
        ?> 
       </div>

Go then to your templates/rhuk_solarflare_ii/css/template_css.css file and change the width to something like;

#header {
 float: left;
 padding: 0px;
 margin-right: 2px;
 width: 100%;
 height: 150px;
 background: url(/ful.jpg) no-repeat;
}

The background url must reflect yours, and not the url above.

In the same file ( templates/rhuk_solarflare_ii/css/template_css.css ), edit the portion which controls the left outer reference to something like:

#left_outer {
  float: left;
 margin-top: 2px;
 width: 165px;
    clear:both;
}

See http://www.w3schools.com/Css/tryit.asp?filename=trycss_class-clear for further clarity, if required.