First of all you need to get involved and Contribute via the mail list, forums, edit the documentation, work on the issue tracker and submit patches.
Once you're contributing and your work is good, one of our Team may invite you to be a committer (after we've called a vote). When that happens, if you accept, the following process kicks into place...
Note that becoming a committer is not just about submitting some patches; its also about helping out on the development and user Discussion Forums, helping with documentation and the issue tracker.
Firstly add yourself to the Team page
Now go read the instructions on the new committers guide. Its also worth viewing http://www.apache.org/dev.
You can find more information about being a committer at Apache here.
Mail the dev list and ask for karma for JIRA / Confluence giving them details of your username you used to register with them both. We can then grant the necessary karma so you can start grabbing JIRA issues or editing the wiki
Mail the PMC chair and ask for karma for Jenkins / Hudson as described here.