Java - sum of prime numbers of random-generated array-values

I am a beginner in Java and I have a task to do, to calculate the sum of prime numbers from the random-generated values of an array.

So, I was told that I should have 3 classes:

1) MyArray - where I have already written this code:

    ...
    public int[] createArray(int n) {
        int[] a = new int[n];

        for (int i = 0; i < a.length; i++) {
            a[i] = rnd.nextInt(10);
        }
        return a;
    }
    ...

2) IsPrime - where I should do the checking if a number is a prime or not. The problem is I don't know how to 'connect' the array from MyArray to the IsPrime class. I started with a boolean method checkPrime, that has an object m from the MyArray class as a parameter, but I don't know how to continue, how to access the array from the IsPrime class.

I am thankful for any given opinions and advice. Thank you!

P.S. My third class Run.java has the main-method.