If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
The first screen you get, when you load the Angry Birds Jigsaw puzzle, gives you 4 options. There is only one image choice in this version of the game, but you get to choose from Easy, Medium, Hard or Expert levels. The easy version of the game gives you 12 pieces, and you get 48, 108, and 192 puzzle pieces for medium, hard and expert respectively. As the next screen loads, the workspace shows you the completed puzzle. You will have to hit the "shuffle" button just below the puzzle to get started.
This game is played with mouse only.