The import isn't that advanced, it's just saying that you want to use the Java API's List interface. However, I doubt that's what you want because that's probably not what your professor is looking for (besides, who likes to use the standard API when you can create the methods yourself?).
All you need is a good sorting algorithm. The simplest to implement are selection sort and insertion sort. Selection sort's slightly easier to implement, but insertion sort is "more efficient" when the list is more sorted.