Code CSS, image de fond sur over-blog

Bonjour,
malgrés avoir parcouru de nombreuses pages, je n'ai pas réussi ce que je voulais faire.
Donc voila, j'aimerai que vous me dites où placer les codes dans mon CSS pour;
- Fixé en fond de blog une image et que celle ci ne se répète pas.
- Rendre transparent les articles

et pour mettre le menu horizontale sous le titre meme si je pense que ca n'a pas de rapport avec le CSS.

J' ESPERE QUE JE SUIS DANS LE BON DOMAINE ! =S

Donc voici mon CSS;


body, html {padding: 0px; margin: 0px;}
#global{padding: 0px; margin: 0px auto; width: 950px;}

.ln {clear:both;}
.cl {float:left;}
.clear {clear:both;}

/* modele */
#cl_0_0 {margin:0px 0px 15px 0px; padding:0px; width:100%;}
#cl_1_0 {margin:0 10px 0 0; width:625px; padding:5px}
#cl_1_1 {margin:0px; width:300px; }
#cl_2_0 {width:100%; margin:15px 0 0 0 ;}
.box {width:100%; overflow:hidden;}/*----------------------------------------------------------------------------*/
/* Variation */
/*----------------------------------------------------------------------------*/
body {margin:0px; padding:0px; background-color:#000000 ; font-family: Verdana, Helvetica, Arial, sans-serif; font-size:x-small; color:#FFF;}
h1 {color: #CCCCCC; font-size: 20px;}
h2 {color: #CCCCCC; font-size: 15px;}
h3 {color: #CCCCCC; font-size: 12px;}
a {text-decoration:none; color:#FFF; font-size:110%;}
a:hover {text-decoration:none; color:#FF6600;}
legend {color:#CCCCCC; padding-left:5px; padding-right:5px;}
img {border:0px none;}
input {border:solid 1px #666; font-size:100%; background-color:#FFF; color:#000000;}

#global {margin:auto;background-color:#333333; border:1px solid #666}

/* ------------------entete ---------------------*/

#top {padding:5px; color:#FFF; background-color:transparent;}
#top h1 {padding:0px; margin:0px; color:#FFF;}
.topLien {text-decoration:none; color:#FFF;}
.topLien:hover {text-decoration:underline; color:#FFF;}

/*-------------------module--------------------------*/

.box {margin:0px; padding:0px; margin-bottom:15px;}
.box h2 {color:#CCCCCC; margin:0px 10px 0px 10px;}
.box-titre { padding:0px; text-align:center;}
.box-footer {display:none;}
.box-content {overflow:auto; padding:2px 5px; color:#666;}
.box-content p {margin:5px 0px 5px 15px; padding:0px; color:#666;}
.box-content ul {margin:5px 0px 5px 15px; padding:0px; color:#666;}
.box-content li {list-style:square; color:#666; margin:5px; padding:0px;}
.listAll{display:block; text-align:right;}

/*------------------- Articles ----------------------------------*/

.article {margin-top:0px; padding:0px; margin-bottom:5px; color:#AAA;}
.article p {padding:0px 0px 5px 5px ; margin:0px;}
.contenuArticle {margin:1px;}
.date {margin-right:10px;}
.afterArticle {padding:3px 0px; border-top:1px solid #666; width:100%; text-align:right; font-size:90%; color:#AAA;}
.beforeArticle {padding:0px 0px 5px 0px; margin:0px; width:100%; color:#666;}
.linkTopic {text-transform:lowercase;}
.linkTopic:hover {text-transform:lowercase;}
.titreArticle {text-decoration:none; color:#FFF;}
.titreArticle:hover {text-decoration:none; color:#FF6600;}
.plusExtrait {margin: 5px auto 10px auto}
.GcheTexte{float:left; margin:3px;}
.DrteTexte{float:right; margin:3px; }
.CtreTexte{margin:3px auto; display:block;}
.hitcitation {font-style:italic;text-align:justify;padding:5px 20px;background-color:#eee;}
.hitencart {border:1px solid black;text-align:justify;font-weight:bold;margin:5px 0px;padding:5px 5px;}
.hitimportant {font-weight:bold;color:red;font-weight:bold;font-size:120%;}
.hitperso1 {font-style:italic;}
.hitperso2 {font-weight:bold;}
.extraitArticle {margin-bottom:15px;}
.titreExtrait {font-weight:bold;}
.afterReactions {text-align:left; display:block}
.afterReactions .linkAddComment { font-size:130%; }
/*--------------------Liste des articles-------------------------*/

.listArticles {margin-top:0px; margin-bottom:10px; border:0px none;}
.resumeArticle {color:#AAA;}

/*--------------------Commentaires---------------------------- */
.h2commentMessage {color:#CCC;}
.comment {}
.comment hr {}
.commentMessage {padding:5px; border:1px dotted #BBB; margin:0px; color:#AAA;}
.commentOption {text-align:right; font-size:90%; color:#AAA; margin-bottom:10px;}
.responseMessage {text-align:right; background-color: #e4e4e4}
.afterReactions .linkAddComment {font-size:130%;}

/*-----------------Newsletter-----------------------------------*/
#divNewsletter {background-color:#333333; border:1px dotted #666;}
#divNewsletter h2 {text-align:center; font-size:12pt;}
#divNewsletter input {background-color:#FFF; border:1px solid #666; color:#000;}
#divNewsletter .newsletter {}
#divNewsletter {}

/* ---------------------Calendrier--------------------------------- */
.calendarTop1 {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 10px; font-style: normal; color:#FFF; font-weight: bold; background-color:transparent;}
.calendarToday1 {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 10px; font-weight: bold; color:#F60;}
.calendarDays1 {width:50px; height:15px; font-family:Verdana, Arial, Helvetica, sans-serif; font-size: 10px; font-style: normal; color:#666; text-align:center;}
.calendarHeader1 {font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 10px; color:#FFF;}
.calendarTable1 {border:0px none;}

/*-----------------------Pagination-------------------------*/
.pagination {color:#000; margin:10px auto}

/*------------------- Pages ----------------------------------*/
.page {margin-top:0px; padding:0px; margin-bottom:5px; color:#AAA;}
.page p {padding:0px 0px 5px 5px ; margin:0px;}
.pageContent {margin:1px;}
.afterPage {padding:3px 0px; border-top:1px solid #666; width:100%; text-align:right; font-size:90%; color:#AAA;}
.beforePage {padding:0px 0px 5px 0px; margin:0px; width:100%; color:#666;}
.divPageTitle h2 {text-decoration:none; color:#FFF;}
.divPageTitle h2:hover {text-decoration:none; color:#FF6600;}

/*----------------erreurs etc------------------------------*/
.error {color : #FFF}

/*----Newsletters-----*/
.newsletter li {list-style-type: none;}
/*----------------------------------------------------------------------------*/
/* Personnalisation */
/*----------------------------------------------------------------------------*/
body {
background-color: #000000 ! important;
background-image: url("http://idata.over-blog.com/2/98/62/52/00280.jpg") ! important;
}
#top h1,
#top h1 a {
color: #ffffff;
font-family: "arial";
font-size: 20px;
}
.contenuArticle, .pageContent, .extraitArticle { background-color: #303030 ! important;
color: #AAAAAA ! important;
font-family: "arial";
font-size: 12px;
}
.divTitreArticle h2, .divPageTitle h2,
.divTitreArticle h2 a, .divPageTitle h2 a,
.titreExtrait {
color: #ffffff ! important;
font-family: "arial" ! important;
font-size: 16px ! important;
}
.box-titre h2 {
color: #CCCCCC ! important;
font-family: "arial" ! important;
font-size: 15px ! important;
}
.commentMessage {
color: #AAAAAA ! important;
font-family: "arial" ! important;
font-size: 12px ! important;
}
.responseMessage {
color: #AAAAAA ! important;
font-family: "arial" ! important;
font-size: 12px ! important;
}