Radiator Leak? Car overheating?

Refill your coolant and let the car run and check where it is leaking. Many GM cars have coolant leaking from the reservoir container or the hoses. These repair can be made easily. Change the hoses with some new ones and remove your reservoir and check it with some water, if it leaks then simply put some epoxy glue on it and it will be fine, I did this for my car. Or you might need a new radiator.

Your gona see it coming out somewhere, just let it run and keep the hood up and watch. Then again, we hope you don't have a leak going back into the engine where the oil is. Thats bad

I agree with both posted mostly. Fill your cooling system with water and let the motor run. Like they said, you will see where it's coming from. I doubt it's leaking into the motor cause after 2 fills you would see your anitfreeze with oil in it but inside the radiator. If it's in the radiator and it's not very big then you have 3 options.
1. Find the hole and use a torch and solder and fix your hole.
2. Buy a bottle of radiator stop leak and use it. It dumps right into the radiator and usually fixes the hole with 100 miles or so. USE CAUTION. Some radiator stop leaks, mainly the ones with metal shavings in them CAN clog your heater core.
3. Replace the radiator. Depending on your car and the store it can range from about $100 up.

If it's in a hose then simply replace the hose. It should only be in place by 2 hose clamps.

If it's the overflow tank then either fix the tank with epoxy or replace it.

If it's the water pump, then you may need to tighten bolt but most likely replace the gasket and maybe even the pump.

Make sure after you fix the problem to use the correct type and portions of Antifreeze. DO NOT USE WATER TO FILL THE COOLING SYSTEM WHEN YOU WILL BE DRIVING THE CAR. Running water alone WILL corrode vital engine/cooling parts and cost u heavily on repairs. I have a 87 grand am and the old owner ran straight water. I have flushed the system twice and it still needs another. Even if you live in a hot climate and there isn't a real risk of freezing, Use Anitfreeze. It also takes a hotter temp to boil. Water can boil in your motor and that produces steam AKA pressure. That can blow your head gasket. Run at least a 50/50 at most a 70/30 mixture of Anitfreeze to water.
Hope this helps.