Here are some links:
A slide show that is a good beginning:
http://nwalsh.com/docs/tutorials/xsl/xsl/slides.html
The wikipedia entry:
http://en.wikipedia.org/wiki/XSLT

XML/XSL are important to be able to receive and send information.

Here is a way to transform a Microsoft Developers Studio project: (remove te spaces betwwen the <

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
<xsl:variable name="newline">&#xA;< /xsl:variable>
<xsl:output method="text"/>
<xsl:strip-space elements="*" />
<xsl:template match="VisualStudioProject">
<xsl:value-of select="@Name" />
<xsl:text>&#xA;< /xsl:text>
<xsl:apply-templates/>
</xsl:template>
<xsl:template match="Configurations/Configuration">
<xsl:value-of select="@Name"/>

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml"
version="1.0"
encoding="iso-8859-1"
indent="yes" />

<xsl:template match="/">
<xsl:element name="library">
<xsl:attribute name="value">
<xsl:value-of select="'My iTunes Library'" />
</xsl:attribute>
<xsl:apply-templates select="plist/dict/dict/dict"/>
</xsl:element>
</xsl:template>

<xsl:template match="plist/dict/dict/dict">
<xsl:element name="track">
<xsl:attribute name="value">
<xsl:value-of select="key[.='Name']/following-sibling::node()[1]"/>
</xsl:attribute>
<xsl:call-template name="artist" />
<xsl:call-template name="album" />
</xsl:element>
</xsl:template>

<xsl:template name="artist">