I think because you left one of the array boxes empty!!
int[][] myArray = new int[3][put a number here as well];
This means that the code should be something like this:
int c = 1;
int mArray[][] = new int[3][3];
mArray[c][c] = 23;
regards,
sim085
Because, array[1] does not exist, since you have not instantiated it. Try this.
int c = 1;
int array[][] = new int[3][/*some integer equal to or greater than 1 here*/];
array[c][c] = 23;
Drake