The simplest but most important way in which you can contribute is by filing an issue. This issue could be a suggestion for improvements, pointing out mistakes either in the documentation or in the information provided by Friendly, or finding bugs.
If you speak a language other than English or French and feel ambitious, you might want to work on translations into your own language.
In most cases, you do not need to create a pull request. If you wish to contribute using a pull request, before doing so please file an issue (unless you have contributed before and are familiar with this project.)