I have never contributed to an open source project, but always wanted to. I thought that contributing to Slim project would be a perfect start for me. After all this page (Contribute - Slim Framework) says it needs me!
I opened this page (Issues · slimphp/Slim · GitHub) (as this page was mentioned in “contribute” section) and… This was not what I expected to see. First, I expected that most of pull requests would correspond to appropriate issues. But only few of them actually was. It looks like issues and pull requests live their separate lives. Second, most of issues there looks more like discussions than problems that need to be solved. People just prefer post their question there and not in this discourse. So those open issues are not actually “a list of outstanding tasks” as was promised. (And some of them are more than a year old.)
I understand how you feel. It can be frustrating when you have the desire to contribute to an open-source project, but you don’t feel that you can make a meaningful contribution. However, it’s important to keep in mind that open-source projects are maintained by volunteers, and sometimes they don’t have the resources to keep the issue tracker as tidy as they would like.
Unfortunately, it is indeed the case that Github issues and PRs are not used as they should be. Some people post their questions there, even though that’s exactly what this forum is for. I have also tried to point this out to some users, but they don’t seem to be interested because they think that they will get more attention or visibility with their question on Github.
Note that even small contributions, such as answering questions, improving documentation etc. can be valuable to a project.