To move a piece of puzzle, follow these instructions:
Place your finger on the piece you want to move.
Keep your finger pressed on the piece you want to move and slide it to another piece.
Put your finger away from the screen to release the piece. It will swap places with the second piece.
Slide the piece of your choice to an available place
The pieces which are at the right place of the puzzle cannot be moved, nor leave their place to other pieces. To spot the pieces left, wait a few seconds without touching the screen. The pieces you can move will be highlighted in white.