Come cambiare colore al Menu

Dopo la domanda precedente riguardante problemi con le miniature, riscontro un'altra difficoltà nella modifica del tema.
Il tema è su ultimatemuscle.altervista.org/blog/
vorrei cambiare il colore dell'header (ovvero dello sfondo della slide) e il colore dei due menù.
Non riesco però a trovare la parte interessata nel foglio di stile css.

/*** Header Navigation ***/

#headernavigation{width:100%;height:34px;float:left; background:#151515;}
#headernavigation div.navigation{margin: 0 auto;width:957px;height:30px;font-size:10px;text-transform:uppercase;}
#headernavigation div.navigation a{text-decoration:none;line-height:30px;display:block;padding-left:18px;padding-right:18px;float:left;text-shadow:none !important; font-weight:bold;}
#headernavigation div.navigation ul{list-style:none;}
#headernavigation div.navigation li{list-style:none;}
#headernavigation ul{float:left;}
#headernavigation li{float:left;}
#headernavigation form.topsearch{float:right;background-repeat:no-repeat;width:167px;height:30px;}
#headernavigation input{border:0;outline:0;}
#headernavigation input.searchfield{background-color:transparent;width:137px;height:12px;margin-top:9px;margin-left:5px;font-size:10px;text-transform:uppercase;float:left;}
#headernavigation input.submitbutton{background-color:transparent;width:23px;height:30px;float:left;cursor:pointer;}
#headernavigation div.icon_holder{min-width:59px;height:23px;float:right;margin-right:5px;margin-top:5px;}
#headernavigation div.icon_holder img{margin-left:12px;border:0;float:left;}
#headernavigation div.icon_holder a{float:left;margin:0;padding:0;background-color:transparent;border:0;background-image:none;}
#headernavigation div.icon_holder a:hover{background-image:none;}

/*** Header ***/

#header{float:left;width:956px;height:86px;}
#header img.logo{margin-top:31px;border:0;float:left;}
#header div.ad{width:468px;height:60px;float:right;background-color:#fff;margin-top:31px;overflow:hidden;}

/*** Categories ***/
#categories{width:953px;height:47px;float:left;margin-left:1px;z-index:100; position:relative; margin-top:40px; }
#categories ul, #categories li {list-style:none;}
#categories a{display:block;font-size:12px;font-weight:bold;text-decoration:none;line-height:47px;padding-left:24px;padding-right:24px; text-shadow:none;}
.cat_line{ margin-left:1px; background:url(images/cat_line.png); width:953px; height:6px; float:left; border:1px solid #eeeeee; border-top:1px solid #fff;}

/*** Category Icons ***/

#left{width:605px; height:100%; float:left;margin-left:1px; margin-top:18px; padding-bottom:50px;} 
#left_not_home{width:600px !important;height:100%;overflow:hidden;float:left;margin-left:1px;margin-top:5px; padding-bottom:50px;}
#left_no_sidebar{width:956px; height:100%; float:left;margin-left:1px; padding-bottom:50px; background:#fff;}
#left div.single{font-size:12px;width:615px;float:left; color:#272727;}
#left div.single a{color:#000; text-decoration:none; font-weight:bold; text-shadow:none;}
#left div.single a:hover{color: #7D7D7D; text-decoration:underline;}
#left div.single h1, #page h1, #left div.single h1 a{font-size:22px;color:#000;font-weight:bold !important;  text-transform:uppercase; background:#fff; padding-right:7px; float:left; text-shadow:none;}
#page h1{margin-bottom:20px;}
#left div.single div.active, #page div.active{float:left; background: url(images/header-line.png) repeat-x; width:100%;}
#left div.single h1 a:hover{border:0; text-decoration:underline;}
#left div.single div.line{width:100%;height:1px;float:left;background-color:#c7c7c7;margin-top:4px;margin-bottom:4px;}
#page div.line {width:100%; float:left; height:1px; background-color:#c7c7c7; margin-top:6px; margin-bottom:16px;}
#left div.single div.date{	float:left;margin-top:12px;width:615px;padding-bottom:13px;}
#left .time{padding-top:4px; float:left;}
#left div.single div.thumb{float:left;padding-top:17px;padding-right:19px;padding-bottom:1px; width:350px; height:222px;}
#left div.single div.thumb img{border:1px solid #DEDBD1;padding:3px; -moz-border-radius: 6px; background:#fff; width:340px; height:192px; -webkit-box-shadow: #dfdfdf 0px 0px 7px; -moz-box-shadow: 0px 2px 7px #dfdfdf;}
#left div.single div.date div.left{float:left;}
#left div.single div.date div.right{float:right;}
#left div.single div.date .date{font-size:12px;text-shadow:none !important;color:#7e7e7e;}
#left div.single div.date .date a{font-size:10px;text-shadow:none;display:block;background:#fff;border:1px solid #CCC;float:left;padding:5px;margin-right:5px;-moz-border-radius: 4px; -webkit-border-radius: 4px; -khtml-border-radius: 4px;border-radius: 4px; color:#999; font-weight:normal;}
#left div.single div.date .date a:hover{border:1px solid #919191; text-decoration:none;}
#left div.single div.content{float:left; width:616px; }
.post_heading{ background:url(images/cat-bg-repeat.png) repeat-x; float:left; clear:both; width:100%; margin-top:34px; margin-bottom:15px;}
.post_heading  .left_heading{font-size:16px; text-transform:uppercase; background:#fff; float:left; padding-right:10px; color:#000; text-shadow:none;}
#left div.related_articles{ width:615px; float:left;}
#left div.related_articles img{ float:left; padding:3px; border:1px solid #c9c9c9 ;margin-top:14px; margin-right:67px; -moz-box-shadow: 0px 0px 7px #d9d9d9;  -webkit-box-shadow: 0px 0px 7px #d9d9d9;}
#left div.related_articles img.last{margin-right:0;}
#left div.related_articles a:hover img{ border:1px solid #8b8b8b;}
#left div.share{width:615px; float:left; margin-top:14px;}
#left div.share img{border:0; margin-right:6.2%; }
#left div.share img.last{margin:0;}
#left div.share a:hover{border:0;}
#left div.author{ background:url(images/author-bg.png) repeat-x; width:585px; float:left; border:1px solid #efefef;  margin-top:14px;  -moz-border-radius:5px;-webkit-border-radius:5px;-khtml-border-radius:5px;border-radius:5px; padding:14px; padding-top:0;}
#left div.author div.icon{float:left; margin-top:14px; width:87px;}
#left div.author div.icon img{padding:5px; border:1px solid #c9c9c9; -moz-border-radius:5px;-webkit-border-radius:5px;-khtml-border-radius:5px;border-radius:5px; }
#left div.author div.icon div.title{width:87px; height:22px; float:left; background:url(images/author-title.png); margin-top:4px; text-align:center; color:#fff; font-size:12px; line-height:22px;}
#left div.author div.icon div.title a{color:#fff; text-decoration:none;}
#left div.author div.icon div.title a:hover{color:#d1d1d1; }
#left div.author div.authorcontent{float:left; width:430px; margin-top:14px; margin-left:7px; }
#left div.author div.authorcontent p{font-size:12px; margin:0; padding:0; color:#747474;}

Grazie per l'eventuale aiuto.

E inoltre non capisco perchè lo sfondo , dal pannello di impostazioni, non funziona! Non inserisce lo sfondo forse perchè c'è già qualcosa impostato nel css, ma non riesco a capirlo ! Chiedo aiuto a qualche staffer di altervista.
Grazie.