All server side source code and documentation resides in the SourceForge SVN. You can browse it from the External Subversion tab above.
All C++ Client (IDE) source code resides in the SourceForge CVS. It needs to be moved to the SVN. Check with a team member if you are interested in working on this component.
You will need a client on your development machine to access the repositories. If you have used SVN's before, you probably have your favorite client. However, if you are new, you may want to talk to a teammate to get a recommendation.