Car rust problems?

get a angle grinder grind off all the rust to clean metal apply filler to build up the metal to the level it was and sand it down with wet and dry paper start with 400 grit then finish with 1200 grit wet and dry then apply primer then spray lightly with a black paint then use wet and dry 1200 sand the area sprayed with black if you still have black areas apply more filler until they disappear when you wet and dry it with 1200 then apply the top coat in thin layers when it is covered then use cutting compound to feather in the old to new paint not easy good luck if it is metallic paint forget it