There are lots of things where you can help, even if you don’t wont to dig deep into the source code. You are welcome to do any of the following things, all of them are very helpful!
Report bugs and problems, such that they can be fixed.
Implement new models.
Update and extend the documentation.
Give feedback on how you like TeNPy and what you would like to see improved.
Help fixing bugs.
Help fixing minor issues.
Extend the functionality by implementing new functions, methods, and algorithms.
The code is maintained in a git repository, the official repository is on github. Even if you’re not yet on the developer team, you can still submit pull requests on github. If you’re unsure how or what to do, you can ask for help in the [TeNPyForum]. If you want to become a member of the developer team, just ask ;-)