OK:
public List<person> List { get; set; }
Other than that, it's a bad idea to expose a collection directly, and it could use either code in the class constructor to create an empty list by default, or a backing field rather than using an automatic property. I'd also make the setter private.
The rest is up to you: it's your homework, and we do not do your homework - it is set for a reason. It is there so that you think about what you have been told, and try to understand it. It is also there so that your tutor can identify areas where you are weak, and focus more attention on remedial action.
So try it yourself, you may find it is not as difficult as you think!