From the command line type cpan Net::Telnet

App::Cpan (the cpan program) installs modules for you. Since you're using Strawberry Perl, it should work for you. You may also want to install (and use in the future) App::cpanminus. It's a little easier to use but less flexible.

You can't just put the module into the Perl binary folder and have it work. Perl doesn't look there for it.

Typing perl -V (capital V) from the command line will give a bunch of information, including where Perl looks for modules. (The contents of @INC)