You got it running and checked everything out, now what?
You could get things running in a VirtualBox VM, or even try it on real hardware.
Check out the GitHub page for more! [https://github.com/SerenityOS/serenity]
SerenityOS is written in C++, so if you're familiar with it you can contribute code. Make sure you read CONTRIBUTING.md first and follow the policies there.
You don't have to be a programmer, you can also contribute art! [https://github.com/SerenityOS/artwork]
Check out the Discord and chat with the community!
You can even watch the developers on YouTube: Andreas, Linus
Or just enjoy it :)