add third colum to layout

hello
this is my first post here and I *think* it may be in the wrong forum.

i am using the following css, and i want to add a third column. so that it goes sidebar, center, side bar. all of the ways Ive tried haven't worked -so i thought id post it here and see what people could come up with.

	body {
		margin:0px 0px 10px 0px;
		background:#333;
		}



	h1, h2, h3 {
		margin: 0px;
		padding: 0px;
	}

	#content {
		float:left;
		width:65%;
		background:#333;
		border-right:1px dotted #999;
		margin-right:15px;
		padding-bottom:20px;
		}

	#links {
		padding-right:15px;
		}

	.blog {
		padding-left:15px;
		padding-top:15px;
		padding-right:15px;
		}

	.blogbody {
		font-family:verdana, arial, sans-serif;
		color:#CCC;
		font-size:small;
		font-weight:normal;
		background:#333;
		line-height:140%;
		padding-left:10px;
		padding-right:10px;
		padding-top:10px;
		}

	

	#menu {
		margin-bottom:15px;
		background:#333;
		}

	
	.side {
		font-family:verdana, arial, sans-serif;
		color:#003366;
		font-size:x-small;
		font-weight:normal;
		background:#333;
		line-height:140%;
		padding:2px;
		}

	.sidetitle {
		font-family:verdana, arial, sans-serif;
		color:#999;
		font-size:x-small;
		font-weight:bold;
		line-height:140%;
		padding:2px;
		margin-top:10px;
		text-align:left;
		text-transform:uppercase;
		letter-spacing:.2em;
		}

	

Thanks in advance
Ruthie