I'm trying to evaluate NetBeans, being a veteran Eclipse user. In Eclipse I could press F4, and I would a class hierarchy for a given class or Interface. For example - show me all the classes that implements InputStream. It's also important it will show me this across all my dependencies and not just my code.
UPDATE: This bug has been marked as fixed, so you should be able to use Find Usages for this.
Original post: You cannot do this without some sort of plugin or other program. The inability to find usages in libraries has been under discussion for 10 years and is currently listed as a Priority 1 enhancement, having no easy workaround. No planned fix date has been announced.