Adding words to a 2-d array

I am doing a Java Wordsearch project for college and I am stuck at a certain part. I am not sure how to add words from a list of strings (input by the user) randomly to the grid. The size of the grid is dynamic; it is based on the the number of words being input by the user, using the following code I've put together: import java.io.* ; import java.util.ArrayList ; public class WordSearchPuzzle