CItrus Perl is provided as a tar.gz archive for Linux and MacOSX and as a zip archive for MS Windows.
Installation instructions are available in the online edition of the Citrus Perl Help Pages.
Once installation is complete you should always use the Citrus Utilities application to check if there are updates available.
The 'Citrus Package' is often updated to provide new capability for the Citrus Utilities application as well as providing bug fixes. When you update the 'Citrus Package' always exit and restart the Citrus Perl Utilities application before managing any other packages.