Non code contributions: OpenNTF users can contribute code but they can also get engaged without contributing code (see here), e.g. by posting ideas in IdeaJam.

Code contributions: For code contributions there are two models for managing code – with different mechanisms for contributions – managed and legacy. The managed model is recommended, and the legacy model will likely be phased out over time. See here for more details about the two models and information about what code you can contribute and how.

There are different levels of involvement possible and different types of OpenNTF users: see here.

See here for further information about to get involved:
Register yourself as OpenNTF user
Committees and working groups
Members
About OpenNTF
Contact OpenNTF
Finding Code via the Catalog
Future
Statistics