Drizzle values community contributions the same as core developer contributions. All contributions, regardless of their author, undergo the same rigorous testing and approval process before being merged into the main code base.
The Drizzle project is hosted on Launchpad which handles code revision control, bug tracking, mailing lists, and everything else needed to manage the project. For most contributions, you will need a Launchpad account.
Launchpad uses Bazaar (bzr) for revision control of the source repositories which includes code and documentation. If you are not comfortable with
bzr, begin by reading the Bazaar documentation. You can practice working with
bzr branches using your Launchpad account.
If you have questions, please ask on the #drizzle Freenode IRC channel or on the Drizzle Discuss mailing list.