First subscribe to the development and/or the users mailing list (see below). You have to be subscribed anyway if you plan to participate.
Before you can do any development you need to be familiar with SourceForge.net and have a user account there.
Important knowledge is to be familiar with wxWidgets and with wyoGuide. The best way to get used to wxWidgets/wyoGuide/wyoDesktop it is just trying out any sample and try to make patches or at least correct bug reports for found problems. If it's not clear if a behavior is correct just ask about in the corresponding user's mailing list.
The usual way of development here is to make patches and send them to the patch tracker. This way any code change gets a chance to be discussed and revised if needed. The optimal procedure for the patch handling is:
Simple text corrections may also be sent to the mailing list but there is no guaranty it is answered and may get lost.
Bug reports are handled exactly like patches but no time frame is given.
The development mailing list is here. The user mailing list can be found in the support section.
Anonymous read access to CVS is possible through
login with password "" (empty) and check out module wyoDesktop.
If you only want to get a part of wyoDesktop (i.e. the CheckDFB) just check out the appropriate subdirectory (i.e. "wyoDesktop/checkdfb").
Directly browse the CVS repository via the web.
See support section.