Inheritance / Extending Classes

Hey,
I’m really confused about inheritance and building classes from other classes.

I have 3 classes:
gfxRoomText - changeable colour
gfxRomInter - changeable colour - interactive
gfxRoomImg - interactive - only image / no colour

The first two incorporate the same text field and functions to change colour.
The second and third incorporate another class to interactive with.
What is the best way of creating these classes using inheritance and how?

Thanks for the help,
Dan