Increasing spacing above menu to show my banner (background image)

I am really new to WordPress and CSS in general.

I am trying to include my banner above the menu in the Zenon Lite theme.
It is 960px by 220px. I have successfully uploaded it as a background image but it is not showing the entire length of the banner (220px). I have read a few posts and tried to increase the padding but it does not seem to change anything. I don’t think I am changing the right one…

My site: fiercepublicity.com
Any help would be great!
The current CSS (hopefully I have included the script I need to change)

*/

body{ background:#f7f7f7; margin:0; padding:0; font-family:Arial, Helvetica, sans-serif; font-size:13px; color:#888;}
.center{ width:1000px; margin:0 auto;}
a{ color:#888; text-decoration:none;}

.postitle a{ color:#333;}

#topmenu ul li a:hover, .postitle a:hover, .zn_post_wrap a, #sidebar .widgets ul li a:hover, .comm_meta_reply a:hover, .logged-in-as a, #topmenu .current_page_item a{color:#D73A36;}

#header{width:100%; float:left;}
.logo{ width:100%; float:left; margin-bottom:25px;}
.logo h1{ text-align:center; margin-bottom:5px;}
.logo h1 a{ color:#333; text-decoration:none;}
.desc{text-align:center;}

.outer-center {float: right;right: 50%;position: relative;}
.inner-center {float: right;right: -50%;position: relative;}
.logo img{ margin-top:15px; margin-bottom:15px; border:none;}

/*SKEW ELEMENTS*/
.skew_bottom_big{ background:#ececec; width:970px; height:70px; position:relative; z-index:-1; float:left; margin-top:-54px;}
.skew_bottom_right{ width:50px; float:right; position:relative; background:#ececec; z-index:-1; height:41px; margin-top:-45px; right:0; bottom:0; margin-right:6px}

.skew_top_big{ background:#ececec; width:970px; height:70px; position:absolute; z-index:-1; right:0; margin-top:-14px;}
.skew_top_right{ width:39px; float:right; position:absolute; background:#ececec; z-index:-1; height:41px; margin-top:-15px; left:0; margin-left:8px}

.single_skew {float: left;margin-left: -15px;margin-top: 12px;position: absolute;width: 662px;}
.single_skew .skew_bottom_big{ width:630px; margin-top:-55px;}
.single_skew .skew_bottom_right{ margin-top:-47px;}
.depth-2 .single_skew, .depth-3 .single_skew, .depth-4 .single_skew, .depth-5 .single_skew, .depth-2 .single_skew_comm, .depth-3 .single_skew_comm, .depth-4 .single_skew_comm, .depth-5 .single_skew_comm{ display:none;}
.depth-1 .single_skew{ margin-top:0px; margin-left:0px; bottom:-12px;}

.single_skew_comm {float: left;margin-left: -15px;margin-top: 12px;position: absolute;width: 662px;}
.single_skew_comm .skew_top_big{ width:630px; position:relative; margin-left:48px; margin-top:-25px;}
.single_skew_comm .skew_top_right{margin-top: -68px;margin-left: 26px;}

#respond_wrap .single_skew{margin-left: 0;bottom: -10px;}
#respond_wrap .single_skew_comm{margin-left: -16px;top: 64px;}

/*MENU*/
#menu_wrap{width:100%; float:left;}
#topmenu{ width:998px; border:1px solid #ececec; background:#fff; height:60px; text-align:center; border-bottom:12px solid #ececec;}
.menu-header{margin:auto; padding:0; display:block;}
#topmenu ul{ margin:0; padding:0;}
#topmenu ul li{ list-style-type:none; display:inline-block; margin-right:15px; margin-top:0px; margin-left:15px;position:relative;}
#topmenu ul>li {height:60px; padding-top:20px;}
#topmenu ul li a{ text-decoration:none; font-size:12px; text-transform:uppercase; font-family:Arial, Helvetica, sans-serif;}
#topmenu ul li ul{ position:absolute; display:none;}