You need to traverse the queue entirely for that, currently you are just showing the info of the first node.
Do something like this :
public void showQueue(myQueue head){
myQueue temp = head;
while(temp != null){
System.out.println(temp.data.toString()); // prints out data at this node.
temp = temp.next; // next should be the link to the next node
}
}
Don't assume my code to be working, rather the opposite, just treat it as a pseudocode for the traversing and printing logic.