Curio is a young project and currently rather experimental. Contributions of any kind that make it better are welcome--this includes both code and documentation.
There aren't too many formal guidelines. If submitting a bug report, any information that helps to reproduce the problem will be handy. If submitting a pull request, try to make sure that Curio's test suite still passes. Even if that's not the case, that's okay--a failed test might be something very minor that can fixed up after a merge and some review (if not, expect some discussion).
It is not my goal to turn Curio into a gigantic framework with every possible feature. If you have built something useful that uses Curio, it might be better served by its own repository. Feel free to submit a pull request to the Curio README file that includes a link to your project.
Also, if submitting a pull request, please consider updating the "Contributors" section of the README file so that you get credit.
Curio uses the py.test tool to write and drive its tests. Probably the best way to get set up to run the test suite is to create a virtual environment. For instance, if you were going to run the tests under CPython 3.5, then you would want to run the command::
python3.5 -m venv venv-cpython35
This will create a venv-cpython35 directory that you can install
py.test into. From there you can follow what the
.travis.yml file
does to run Curio's test suite (both for code and documentation).