如何做到网站主页刚出来就显示一个页面,或一个图片,几秒钟就没了!!!

1.网站主页:
<script language="javascript">
    window.open("somepage.html","_blank","width=200,height=100");
</script>2.somepage.html:
<script language="javascript">
   setTimeout("window.close()",5000);
</script>
Your content here