I can now move pieces! But there is no legality check yet. I also added a green outline if you select a piece. It works by listening for a click. Then when it gets a click it takes mouseX and mouseY and divides by positionSize to find which row and column it is on. It then checks against the board to see what is on that position. If it is a piece then it creates an outline and sets that as the active square. If it is empty AND active square has a value, it moves the piece.