高校突发卫生公共事件:怎么把下面的代码写成一个CSS文件,,然后怎么调用???

怎么把下面的代码写成一个CSS文件,,然后怎么调用???

<style type="text/css">
/*<![CDATA[*/
* {
margin: 0;
padding: 0;
}
html, body {
height: 100%;
text-align: center;
font: 12px/1.4 Verdana, sans-serif;
background: #F00;
}
#wrapper {
width: 1000px;
min-height: 100%;
background: #ccc;
margin: auto;
text-align: left;
}
* html #wrapper {
height: 100%;
}
#header {
background: Green;
height: 60px;
}
#header-a {
background: Green;
height: 10px;
}
#content-title {
text-align:center;
font-weight: 800;
FONT-SIZE:12pt;
background: Green;
height: 40px;
}
#sidebar {
float: left;
width: 200px;
background: Gray;
}
#content-text {
float: right;
width: 570px;
height: 200px;
background: Gray;
}
#content-box {
float: right;
width: 570px;
background: Olive;
}
#headleft {
font-family: 华文彩云;
FONT-SIZE:33pt;
float: left;
width: 200px;
height: 60px;
background: Gray;
}
#headright {
float: right;
width: 570px;
height: 60px;
background: Olive;
}
#footer {
height: 50px;
background: Background;
width:770px;
margin: auto;
}
/*]]>*/
</style>

代码在title内