Instructions
Move your rook horizontally across the board. A rook can move as many squares as desired in a straight line provided no other pieces are in the way. The rook can never move diagonally. For example, the rook cannot move as your starting move, because it starts the game surrounded by pieces.
Avoid moving the other rook or your king throughout the game. In order to make castling legal, a move in which you can move the rook and the king simultaneously, you cannot move either of these two pieces prior to the move.
Move any of your pieces between your rook and king. Castling cannot occur unless the space between the two pieces is empty.
Castle. Move your king two squares toward the rook you are using to castle. Place the rook where the king originally was placed.