That means that you need to install a YAML module or a JSON module. CPAN will let you choose which module that you want. I've had problems with YAML, so I always choose YAML::Syck. So, sudo to cpan, then
cpan> install YAML::Syck
cpan> o conf init yaml_module
cpan> o conf commit
Put it somewhere bash looks for it and you are good to go!
A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James