Style Sheet

Hello,

I'm wanting to add some css code to my main one,but it does not display right,and cant figure out what i'm doing wrong
(i'm kinda new to this)
here is an example of what i'm after!https://i.servimg.com/u/f64/14/84/32/66/wowhbb10.jpg

and here is the code i would like to add(images are uploaded in root folder)
html {
font-size: 100%;
}

body {
background: #000 url('./images/horde-tile.jpg') repeat-x top;
font-size: 62.5%; /* This sets the default font size to be equivalent to 10px */
margin: 0;
scrollbar-face-color: #202020;
scrollbar-highlight-color: #606060;
scrollbar-shadow-color: #303030;
scrollbar-3dlight-color: #202020;
scrollbar-arrow-color: #E0E0E0;
scrollbar-track-color: #000000;
scrollbar-darkshadow-color: #202020;
}

#wrapheader {
min-height: 135px;
height: auto !important;
height: 135px;
background: TRANSPARENT url('./images/background.gif') repeat-x;
padding: 0;
}

#wrapcentre {
margin: 15px 25px 0 25px;
}

#wrapfooter {
text-align: center;
clear: both;
}

#wrapnav {
width: 100%;
margin: 0;
background-color: #ECECEC;
border-width: 0px;
border-style: solid;
border-color: #A9B8C2;
}

#logodesc {
margin-bottom: 15px;
padding: 0px 10px 0px 10px;
background: TRANSPARENT url('./images/headerbg.jpg') repeat-x;
border-bottom: 0px solid #000;
}

#menubar {
margin: 0px;
background: transparent url('./images/menubarbg.gif') repeat-x;
height: 24px;
}

#datebar {
margin: 10px 25px 0 25px;
}

#findbar {
width: 100%;
margin: 0;
padding: 0;
border: 0;
}

.forumrules {
background-color: #F9CC79;
border-width: 1px;
border-style: solid;
border-color: #BB9860;
padding: 4px;
font-weight: normal;
font-size: 1.1em;
font-family: "Lucida Grande", Verdana, Arial, Helvetica, sans-serif;
}

.forumrules h3 {
color: red;
}

#pageheader { }
#pagecontent { }
#pagefooter { }

#poll { }
#postrow { }
#postdata { }
btw do i need to change something to my htlm temp,aswell then?,if so could you guide me trew it , or provide me with a topic that has the same problem ?
(i use phpbb2)

kind regards