The starting point for YaST development can be found at the YaST landing page at Github.io. It includes links to the repositories of source code, documentation and guidelines.
For more general user oriented information, see the YaST Portal.
If you have any question, feel free to ask at our mailing list or at the #yast IRC channel on freenode. We'll do our best to provide a timely and accurate answer.
You are welcome to edit this page, but please refer to The Vision to keep it consistent.