If you're interested in following or participating in Nengo development, please join the developer's mailing list.
Nengo uses subversion (SVN) for version control. That means that the source code for Nengo lives on a central server (currently ctnsrv.uwaterloo.ca) and you must use an SVN client to interact with the server. You can either set up a standalone SVN client, or use an SVN client integrated with your IDE.
While you can edit the source code for Nengo using any capable text editor, we recommend setting up a robust IDE (integrated development environment) so that you can use one tool to edit source code, build the application, and debug it if necessary. Since Nengo is primarily a Java application, we recommend using the multi-platform IDE Eclipse. You can even access and interact with our SVN servers from Eclipse.
The first step in setting up a development environment is to set up an SVN client. Below are guides to setting up SVN from the command line, with the standalone client RapidSVN, and from within Eclipse using Subversive.
The second step is to set up an IDE, if you choose to use one. There is a guide to setting up Eclipse below. If you're going to use Subversive as your SVN client, follow that guide before following the one on Subversive.
Development guides: