castling

I have read about six posts on castling in 960, as well as the unhelpful help screens. Can anyone tell me how to castle as Black in this position? I mean what do I drag where to make it happen?

The king and rook have not moved but I can't seem to castle.

Thanks

I meant to castle king-side. Queen-side works OK.

Castling in 960 always works (when legal) by moving the king onto the rook.

Note that in this position, you can only castle h-side, where the king and rook will end up on the g8 and f8 squares, respectively.  Castling a-side is not legal because the king and rook would end up on c8 and d8, yet the d8 square is not empty.

Thanks. What you say is correct.