The easiest way to checkmate with king and rook against king is to follow this process: 1. Use your rook to put the opposing king in a box. 2. Bring your king towards the rook to protect it. 3. If it's possible to shrink the box with the rook each turn, do it. If not, move the king closer to the opposing king. 4. Once the opponent's king is on the edge of the board checkmate by using the rook with your king covering the escape squares.
