I can change the fill color, but there is no way to actually fill any shape etc.
I still have no idea how it works. Apparently this robot is not going to reply.
Which robot are you talking with?
Select the object. Either on the Side Bar or with a right click, you can access to the “Area” controls. Under “Fill” you can choose between Colour, Gradient, Hatching, Bitmap or Pattern. With Bitmap you are not limited to the predefined images: you can import any picture, including vector formats.