If you want to contribute to the QuantLib project, there are a number of things you can do. Possibilities include:
- contribute code to the library. Opening a pull request on GitHub would be the easiest way to get your contribution into the QuantLib code tree; see these instructions for details.
- provide examples. Those are easier to write than new parts of the library, and are very useful to new users as they can act as documentation of library features and their usage.
- subscribe to the QuantLib-users mailing list and answer questions there. This requires less coding experience, and is very useful since the developers can't dedicate a lot of time to it.
- report any bugs you find to the QuantLib-users mailing list. This will help us improve the quality of the library.
Even if contributions were little, their cumulative effect would be a great help to improve the library. Moreover, each of the above are also ways to familiarize with the library and to establish yourself as a trusted contributor.
Finally, we might need to ask for a disclaimer from your employer stating that your contribution can be released under the QuantLib license. Such disclaimer won't be necessary if you own the copyright of the code, but you might want to check that with your employer. An example of such disclaimer can be downloaded here, but you can write your own along the same lines if the wording doesn't suit your employer.