go to greenfoot.org/book then click on book scenarios under students. it probably downloads as a zipped file, so you'll have to right click on the folder and click extract all. then if you go to the scenario asteroids-3 in chapter 7, you'll find an example of a scoreboard that pops up when the game is over. It doesn't count the score yet, so you'll have to add that part yourself, but it does come up at the end like you want. You can study how that is implemented and try to mimic it. I'd give you more specific help, except I'm struggling with scoreboards myself right now, but if you run into problems and/or have any specific questions feel free to ask, and if I can't help someone else can I'm sure :)