Thank you for writing.
You can refer to the following help article demonstrating how to setup RadDiagram
with shapes and connections: http://docs.telerik.com/devtools/winforms/diagram/populating-with-data
As to the manipulation at runtime, you can disable the selection functionality
and thus the user won't be allowed reconnect shapes, resize them etc.
I hope this information helps. Should you have further questions I would be glad to help.