Checkers is played on the dark squares only. A piece may move one square at a time, diagonally. If one of your pieces is next to one of your opponent's pieces and the square beyond it is free, you may jump over the opponent's piece. The opponent's piece is then removed from the board. It is possible to jump many times in a row with the same piece, capturing several of your opponent's pieces.
In the beginning, pieces can only move and jump forward. However, if a piece reaches the far end of the board, then it becomes a king. (In checkers, a king is usually signified by stacking two checkers one on top of the other. In this program, the king has a star on it.) A king is allowed to move and jump diagonally backwards and forwards. Kings can be captured like any other piece.
You win by capturing all of your opponent's pieces, or by blocking them so that they cannot move.