You could implement such a heap sort. However, there is no need to do so, unless for practice or for homework.
Java provides a variety of ways of sorting.
First, your Friend class needs to implement compareTo(), equals() and probably hashCode(). Your implementations of these should compare the ages first, as that's the main thing on which you want to sort. If the ages are equal, then the comparison should move on to the name; you must do this, otherwise two different people with the same age will be considered to be the same Friend, which would be wrong.
The java.util.Arrays class provides methods that can be used to sort arrays. In your case, you'd use the version that takes an Object.
The java.util.Collections class provides methods for sorting a List. Storing your Friends in a List could be a good idea, to make it easier to add and remove entries.
Lastly, and possibly best, if you store your Friend objects in a SortedSet, they will always be kept in order automatically. You never actually have to sort them.