The XML::LibXML module provides an XS wrapper around the libxml2 library so if you're building from source then a compiler is required. But building from source is not usually required. A PPM for ActivePerl on Windows is available as documented in the Perl XML FAQ. For Linux, simply install the appropriate package from your distribution (eg: 'apt-get install libxml-libxml-perl' on Debian) and dependencies will be resolved automatically.
If you have a problem that you want help to solve, then perhaps you might like to tell us what you tried and what happened.