You create new objects by using the
new operator.
You can pass these objects to other methods or, also other methods in other classes, or to constructors of other classes. You already have a complete program in which you're passing around objects all the time from method to method.
So surely you must already understand how to pass objects from one place to another, as arguments to a method or constructor. That's what you originally asked, but it's apparently not what your question is really about.
If you want to have one ClockFrame to which you add a ClockPanelAnalog and also a ClockPanelDigital, then you shouldn't put creating the ClockFrame in ClockPanelAnalog.
You should probably create the ClockFrame in your main method, in class TimeGenerator, and then pass the ClockFrame object to the constructors of ClockPanelAnalog and ClockPanelDigital, which can then add themselves to the ClockFrame.