put this in custom header::

<style type="text/css">
body {
 background-image: url(http://www.twilightanime.com/wallpaper/Naruto01-800.jpg);
 background-repeat: yes-REPEAT;
 background-attachment: FIXED;
 background-position: bottom,left,top,right;
 background-color: #000000;
 scrollbar-arrow-color: #0000cc;
  scrollbar-track-color: #ccccff;
  scrollbar-shadow-color: #000000;
  scrollbar-face-color: #000066;
  scrollbar-highlight-color: #000000;
  scrollbar-darkshadow-color: #000000;
  scrollbar-3dlight-color: #0000cc;
  }
.left, .blogbody, table.footer, .standard, .leftmodulefontcolor, td, p {
/* edits main text */
  font:normal 10px verdana;
  line-height:11px;
  color:#ffffff;
  letter-spacing:0px;
  text-align:justify;
  }
table.footer TD {
/* this makes the footer at the bottom centered */
/* leave it alone unless you know what to do*/
  text-align: center;
  }
div.blogheader, .caption {
/* edits the dates */
  font-family:arial;
  text-transform:lowercase;
  font-size:25px;
  line-height:17px;
  font-weight:italic;
  color:#0000cc;
  letter-spacing:0px;
  background-color: #colorcode;
  text-align: left;
  border: 2px solid #57C9F9;
  }
a:link, .footernav.link, a.footernav:link, a.footernav:active {
/* edits all links */
  color:#Colorcode;
  text-decoration: none;
  }
a:visited, a.footernav:visited,  {
/* edits the links that the user has visited */
  color:#Colorcode;
  text-decoration: none;
  }
input, select, textarea, .textfield, .button {
/* this edits the buttons, dropdowns, etc. */
  border: 2px solid #000066;
  font:normal 10px verdana;
  background-color: #colorcode;
  letter-spacing:0px;
  color: #000000;
  }
table.left {
/* this edits the menu module */
  border: 6px solid #0000cc;
  width:160px;
   background-color: #Colorcode;
   color: #000000;
  }
table.blogbody {
/* this edits the other the place where the  blog is */
  border: 3px solid #000066;
  background-color: #colorcode;
  width:450px;
  }
table.left th {
/* on your menu module, this edits the title part of it */
/* like BLOGRINGS, POSTING CALENDAR, etc */
  background-image: url();
  background-color: #colorcode;
  font: bold 11px tahoma;
  text-transform: lowercase;
  color: #000066;
  border: none;
  text-align: center;
  }
table.left TD {
/* on your menu module, this edits the body part of it */
  background-image: url();
  background-color: transparent;
  border: none;
  color: #Colorcode;
  }
table.search TD, table.search, table.announcements {
/* border of search bar (if you have it) */
  background-color: transparent;
  border: 2px dashed #Colorcode;
  }
table.search TD, table.announcements TH {
/* this should be left alone */
/* unless you know what to do */
  border: 0px solid #Colorcode;
  }
table.navigation, table.main, table.footer {
/* the width of your blog with modules */
  width: 500px;
  }
hr {
/* horizontal divider */
  border: 1px solid #Colorcode;
  }
</style>