Are you asking how to add CAM::PDF to the modules you have available? If so, and you're using ActiveState's distribution, try ppm help. Alternately, read Yes, even you can use CPAN (and the various other nodes (hint: Super Search) explaining how to install and use modules.

On the other hand, if your question is how to use a specific module, read about it at CPAN or http://search.cpan.org/... or just use perldoc CAM::PDF on the command line to read its internal explanatory material.

Seems the word "read" comes up again and again: For example, please also read On asking for help and How do I post a question effectively?.

In brief, read, learn, code and then ask specific questions when you get stuck.