The first system we're going to show you uses a simple 9 space grid, which resembles a noughts and crosses board (a tic-tac-toe board to anyone outside the UK).
In the boxes we place our letters, we then use a marker to indicate which letter in that box we are referring to. The marker position corresponds to the letter location - left, middle or right.
Try using what you've learnt to crack our cypher. (Answer is in the video see here.)