I have a '98 Pontiac Grand Prix GTP and it is overheating. What can I do to fix this problem?

It is overheating when I am driving. There is buildup of rust in the radiator opening. I think that might be the problem but I am not sure. There is also orange rust colored stains on the engine and its melting the pad connected to the hood. Is there something I can do myself to fix this problem without using very much money?