Dev Getting Started
How do I get started doing Dreamwidth development?
The best place for anybody to start out for Dreamwidth development is #dw_kindergarten, where there people willing to mentor who can figure out where your abilities are at and how to best apply them.
People wanting to work on a provided development environment should look into requesting a Dreamhack.
If you have the means and desire to install your own development environment, there are resources in the Dreamwidth Installation category. The original LJ Server documentation is here. You might also find the LJCode wiki useful.
Basic guides
To browse the Dreamwidth code, you can look at the Mercurial repository; the main parts of the code you will be interested in are in dw-free. To see the changes being made to the Dreamwidth code, look at changelog, which automatically posts commits.
You can find information on how to keep your code updated on Dev Maintenance, information on programming style on Dev Programming Guidelines, information on finding things in Dev Finding Things, and information on submitting patches on Dev Patches. There is a comprehensive bug list as well as other useful info on Bugzilla. See Development for a more complete reading list, or look through the pages in Category:Development.
Developers should check out the documentation on Design as well.