This code is, to a great degree, shamelessly lifted from example/twitter in the Net::OAuth::Simple library.
To install Net::FreshBooks::API, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Net::FreshBooks::API
CPAN shell
perl -MCPAN -e shell install Net::FreshBooks::API
For more information on module installation, please visit the detailed CPAN module installation guide.