Je n'arrive pas a rooké depuis un moment
The site has changed castling to remove the ability to click the king and then the rook to castle, at least by default. If that is what you want to do you need to change the Castling Method under Settings > Board and Pieces to Legacy from Normal.
If you prefer to use click-move, you can click the king and then the destination square under the Normal setting. With drag-move you can drag to the destination square or drag the king to the rook
Je n'arrive pas a rooké depuis un moment