http://www.w3schools.com/xsl/xsl_languages.asp got a friendly tutorials on xsl,xpath,xsd and so on. do read them
Your xslt gives error because xsl:if
test condition should go under test attribute of xsl:if..
something like..
<xsl:for-each select="caseinformation">
<xsl:if test="$regionvalue=region"/>
--execute rule--
</xsl:if>
</xsl:for-each>