Car Won't Start PLEASE HELP

I am having serious problems with starting a car which is usually kept garaged in the cold. It has no current serious problems on the internals. My car is a 2001 VW Cabrio(really a Rabbit with convertible top), We are outside, weather is about 15 below 0 degrees F(Chicago area). The car was out of radiator fluid and we just refilled it with 100% radiator fluid, and light was on 3 days. We tried also adding Heet(gas line defreeezer) to the gas tank, jump starting, and allthough the lights and radio work fine, the car will not start. The car clicks when ingition turned with a sort of clackety repeating sound at even intervals. Car wil not turn over, although it does not seem to drain the battery. Please, if you have any idea what it might be and a cheap, quick, or resonable fix, it would be a big help to us. Thanks.

Your post is confusing.
What do you mean when you say “Light was on three days”? What light? Was an interior light left on which may have zapped the battery?
Please tell us more about the coolant. You indicate that 100% coolant was added. Does your owner’s manual spec 50/50 or 100%? If the coolant was gone, there is a reason that it went away, so starting the engine before this is sorted out may lead to other issues…
The noise that you describe so well is your starter trying to engage. It sounds like you have the voltage in the battery to run the lights, but you lack the AMPS to feed the starter. How old is the battery? Are the terminals and cables clean? Is it possible that the engine has seized? (Perhaps due to lack of coolant?) Does it have a manual transmission so that you could attempt to push start it?

Yes, you may have a serious coolant system leak. This needs to be fixed right away.
When you are trying to start the car, open the hood and listen to WHERE in the engine compartment the CLICKING is located. The clicking might be in the relay box; or, it might be on the starter. Let us know which.
Put the gear selector in N when you try to start. Results?

The system coolant light was on for about three days, and we neglected to take care of the problem immediately because we are female (even at the advice of our boyfriend). The car ceased to operate last night when we were attempting to leave a relative’s house. We added the proper mix of coolant to the system. We also added HEET gas line defreezer. We also tried jump starting the car by running off a relative’s auto for about 15-20 minutes. We also tried to start the car in Neutral. The battery was purchase about 1-2 years ago. It is not manual transmission, so we can’t push start it. We also have about 1/2 tank of gas in the vehicle.