Java queue using linkedlist

I am struggling with an assignment. The goal is to fill in blanks in a queue implementation using linked list and write an output. All the code with stars (****code****) are those blanks that I filled, some of them very likely wrongly filled and - I don't fully understand why.

If someone could point me in the right direction, fix the code or explain what did I fill wrong and why, I would be grateful.

Thank you, Timmy

public class DoubleQueue { public class QueueEmptyException extends RuntimeException{};

private **class** Node{
    double num;
    Node next = null;
    Node (**double** num) {**this**.num = **num**;}
}

private Node head = null;

public void push(double num){
    Node tmp = **new** Node(**num**);
    tmp.**next** = head;
    head = **num**;     
}

public double pop() throws QueueEmptyException {
    if (**num** == null) throw new **QueueEmptyException**(){
    Node node = head;
    if(node.next == null){
        head = null;
        return node.**next**;
    }
    while (node.next.**next** != null)
        **node** = **node**.next;
    }
    double ret = aux.next.**next**;
    aux.next=null;
    return ret;
    }
}


DoubleQueue queue = new DoubleQueue();
queue.push(17);
queue.push(23);
queue.push(15);
System.out.println(queue.pop());
System.out.println(queue.pop());
System.out.println(queue.pop());

What is the console output? 1. _____ 2. _____ 3. _____