Magento add Css into CMS

<reference name="head">
    <action method="addCss"><stylesheet>css/magento_u.css</stylesheet></action>
   <action method="addItem">
       <type>skin_css</type>
       <name>css/ie.css</name>
      <params />
      <if>lte IE 8</if>
   </action>
</reference>