Hi Alexandru,
Thanks for evaluating Syncfusion Products.
The Help Documentation for SfDiagram version of WPF is in progress. As we are using the same code base for SfDiagram version of Winrt and WPF. Please refer to the online help documentation of Winrt from the following link.
Link: http://help.syncfusion.com/winrt -> SfDiagram
For more details, please refer to our SfDiagram Dashboard Samples from the following navigation link.
Link: Dashboard->WPF->Diagram.
Please let us know if you require further assistance on this.
Regards,
Ranjitha A.