xml and xslt problem

hi, i'm having a really tough time figuring this one out. i have an xml file that has the content for multiple pages. i also have an xslt file that picks that appropriate page from the xml, parses it and gives that to the code behind that then posts it into a place holder. my issue is this. when a user clicks a link like about.aspx?page=whatwedo, i need to take that argument and pass it to the xslt file so that i can match the appropriate section so ideally i could do something like: xsl:for-each select="$section" where section is: xsl:param name="section" a parameter that i set from the C# code behind. But that doesn't work. How can i go about doing this? my eternal gratitude to anyone who can help me out. Thanks...