When you first see the puzzle there will be a menu in the middle like this.
The yellow highlight will open a tab on the left to reveal the number of puzzle pieces. You can pick a lower number to make it easier or a higher one to make it super hard.
The green highlight will rotate the puzzle pieces.
And the blue highlight will change the background colour.
At the top of the puzzle is another menu.
The yellow highlight will bring back up the menu in the middle again.
The green highlight will make a puzzle piece disappear when you click on it and if you click on it again any pieces you have hidden will reappear.
The blue highlight will just show you the edge pieces and when you finished the edge it will reveal all the inside pieces. Or, you can just click on it again to show all pieces.
The pink highlight will show you what the picture looks like that you are making.
The orange highlight will put the puzzle into full screen. Once you are finished just click the escape button to return to the page.