Choose the puzzle's number of pieces (between 2x2 and 16x16).
Shuffle the pieces.
Move the shuffled pieces from the bottom right to the bottom left area by clicking on a piece and clicking again on a target cell.
In the bottom left area, you can swap 2 cells by dragging and dropping a piece.
To help your moves, use the "Grid" option, which tracks the mouse.
The "Analyze" button shows you the misplaced pieces; they are red framed (this button is active only when the "Grid" mode is on).
The "Solve" button solves the puzzle for you.
A score is computed according to the difficulty's rate, time spent, number of moves and number of times you hit the "Analyze"/"Solve" buttons
After you move all the pieces from the bottom right to the bottom left, you will be propmted with your score and a congratulations message. However, this doesn't necessarily mean that you are done. Hit "Analyze." The red framed pieces, if there are any, are misplaced and should be repositioned.