I think i need to recreate it. but it is fairly simple can anybody give me examples on how to do greenfootgetrandom number and everytime it comes up with a certain number iit adds an object to the world. in the background class. Also how to do a public int speed and set an object to that speed. and everytime time i click an specific object, the speed of the car increases by one? I am so new to programmming

No. A greenfoot file is a single file within a scenario folder that contains certain information about the specific project. It would not be your project as a whole. You said you had a compressed file. Right-click on it and select 'Properties' from the menu. The file type should be shown including its filename suffix.