Can someone please put up the code that I would need to add and actor to a world fro within another actor (so when my car passes moves a person is added to the screen).
To add an actor to the world you have to use the method addObject(Actor, int, int);
Using this method you add an actor to the world at the coordinates you give the method (the int's).
When you want to add an actor from another actor class you need to use getWorld().addObject(Actor, int, int);
You can also look this up in the Greenfoot API. All mehtods are listed and described there.