There are a number of reasons why you should get involved and various ways to actually do so. What are your interests?
The best way to get to know a software is to use it! Implement features that you yourself need – new software, code snippets, adaptations, extensions, etc. Help others solve their problems. Fix bugs and enhance the existing software. There are many ways to get started!
Contact the community leader who is responsible for the software to which you would like to contribute. If you are interested in providing code, you will need to sign our contributors license agreement (CLA). Follow the CLA step-by-step guide. If you have questions about this or our software licensing, please check our licensing pages.
The development of high quality software demands a lot of testing. Run the latest development code and provide feedback on changes as they occur. Report errors or possible improvements via GitHub issues. We also have various mailing lists in which you can report bugs.
Help produce official software documentation, i.e. user guides, tutorials, how tos, FAQs, etc. Document a solution to a problem. Check, proof and test documents for accuracy. Contact the community leader who is responsible for the software documentation in question.