Welcome to the Ranch.
You need to set some sort of size, or bounds for your frame before trying to make it visible.
When you see the frame, the panel will be inconspicuous, because you can't see it until you do something to it. Try setting the background of the panel to a particular colour with the
java.awt.Color class.
All the methods are in the documentation for
JPanel and
JFrame, but you might have to hunt through the blocks of "methods inherited from . . . " to find them.