How I can add a polygon (Geometry) to a Layer?
I need to add it to Map.Layers for editing once it is drawn.
And one more question, how I can save locally?
Thanks in advance.
Hey, to get started please see following documentation
Edit features—ArcGIS Runtime SDK for .NET | ArcGIS for Developers
Create an offline map—ArcGIS Runtime SDK for .NET | ArcGIS for Developers