SWFObject的相关问题

我要在网页中插入一个特效，这是原有代码，可是出来的效果背景是黑色的，我想去掉背景用我自己的背景怎么办？<SCRIPT type=text/javascript>
var so = new SWFObject("flash/viewer.swf", "sotester", "990", "480", "9", "#000000");
so.addParam("wmode", "opaque");
so.addParam("flashvars", "&xmlLocation=images/nifengla.xml");
so.write("loader");
</SCRIPT>
还有一个问题不理解SWFObject("flash/viewer.swf", "sotester", "990", "480", "9", "#000000")中的参数都代表什么啊？