A good place to start is here at perlmonks.

Read the posts here. Understand them. Find and offer answers to questions and solutions to problems. Through this you will practice and learn a lot about perl, learn a bit about what help others need, what interests you and where you have the ability to contribute.

Eventually you may find problems for which the best solution is an enhancement to a Perl module, or a new module or even a bug fix or enhancement to perl itself.

When you have a specific objective in mind you can ask for guidance here. You will receive good advice, including pointers to other forums when they are appropriate.

Through this you will be participating in the Perl project, practicing and learning.