Need help with XSLT: adding new node btw existing ele

I have the following input xml document, I need to write an xsl to transform
it to the output xml document.

<?xml version = '1.0' encoding = 'UTF-8'?>
<test xmlns="blabla">
<comp id="New">
<process-type id="home" module-id="TESTER" status="enabled">
<environment>
</environment>
</process-type>
</comp>
</test>

<?xml version = '1.0' encoding = 'UTF-8'?>
<test xmlns="blabla">
<comp id="New">
<process-type id="home" module-id="TESTER" status="enabled">
<environment>
<variable id="SAROOTDIR" value="D:\Dir1"/>
<variable id="SADATADIR" value="D:\Dir2"/>
</environment>
</process-type>
</comp>
</test>

Can someone please help write an xsl to transform the above input xml
document into the output xml document?