I been told it is quite hard to do it by myself, cuz need some tools and special material, anyone got toturial? I am going to fill the panel, looks nice,.

Go to home depot get a can of Great stuff expanding foam
Next remove the frame from your car and line with tinfoil.
spray great stuff in tin foil lined license plate frame holder thingy.
wait till it hardens (says on can)
once its hard take a serated knife and cut down excess to be smooth with frame.
sand it soomth and to contour with the LPholder shape.
Fiberglass over the entire thing, body fill and smooth. paint