Is there a tutorial where I can learn how to use the Cpan modules

Take a look to the module section in the Tutorials. If perl is a new land to you, try first to build a solid basis, so read also the basic tutorials first.

Using a module implies

1-Download and install the module in your system, i.e with

cpan install a::module::name

The core and Very Important Modules are available directly with your perl installation, no need to download or install this

2-Put a line like this in your script:

use a::module::name;

Now you can call the functions provided by this module in your script with something like:

my $var = &function( "required function args here" );

Really, how to use the funcion ranges between very easy and really esoteric. All modules in cpan have your own documentation and examples (generally in the same page as the download link), but its true that some are poorly documented and you will need to guess how to fill the gaps.