How to use methods from class extended for my object existing?

How to use methods from class extended for my object existing?

I have a object JTextPane stored in HashMap. I pick up that object in a
class separate with constructor. Basically:
public MyClass()
{
JTextPane jTextPane = HashMap.get(Object);
}
This class is responsible for handle the object JTextPane. As for example,
change font, get text selected, so on. These methods already have in
JTextPane class. So, I not going need create it. So, enough I extend the
class JTextPane. Now, if I create a object MyClass, I going to have access
to methods JTextPane, for use with my object existing then, I can to call
the methods, however, not is working. I try use the super(); but, not it
worked.