The best way to contribute to the Apache Software Foundation (ASF) is to get involved with one of our many Apache project communities. The best way to ask general questions about community involvement is to read about Community Development at Apache.
The ASF is made up of over 300 different projects, with many new project submissions (or podlings) coming into the Apache Incubator every year. So no matter what kinds of technology or software you use, we most likely have an Apache project that you'll be interested in.
Using Apache products, asking (and sometimes answering) questions, reporting bugs and making feature requests are critical contributions to the success of the Apache project community. User feedback helps drive our projects and the technologies behind them.
Beyond simple user activities, it's great to see users becoming contributors by helping with the development of Apache projects. This can mean getting involved with the discussions on the development mailing lists, answering other users' questions, providing patches for bug fixes or features, and helping to improve developer and end-user documentation.
Understand How It Works and see other notes for contributors
We love to see contributors showing commitment. Projects invite committed participants to become committers and help shape the future of a project.
Apache is a meritocracy. Once someone has shown sufficient sustained commitment to a project by helping out and contributing work to it (and the ASF), the project may vote to invite that person to become a committer.
How does one show commitment?
Get involved and contribute via the user and developer email lists, Wiki and forums (if any); extend or improve the documentation; work on bugs listed in the issue tracker or submit code patches. Answering other users' questions is a great way to get started, as is suggesting patches or improvements to Apache project websites.
Note that becoming a committer is not just about submitting some patches; it's also about helping out on the development and user discussion lists, helping with documentation and the issue tracker, and showing long-term interest.
For more on how to get involved and the open source mentality, see:
Contributing -- Craig R. McClanahan
Understanding Open Source -- Cameron Riley
Producing Open Source Software -- Karl Fogel
For more technical information, see ASF development infrastructure and notes for committers.