First....be forwarned I'm 16 and this is my new car, I'm not hopeless when it come to things under the hood, (oil changes, spark plugs, etc. are fine) but this car is new to me.

Yeah, I thought it at first, that it just might be wiper fluid, (and hoped!), but alas, the expansion tank for the coolant was just barely above minimum (I checked it was halfway between last week). So, now I know its antifreeze, so I looked under the hood, hopefully to find it was just a hose (a.k.a cheaper than a cracked radiator). With a flash light I could see the wet area, right around a drainage hole(for water or A/C condensation I presume). I couldn't trace it back to the radiator, tried getting my hand down there and up from underneath, no luck, it seems to be right under a cylinder shaped tank right against the front wall of the car, with a hose leading in. My question is is this a pump in the coolant system or what?
So, I mixed some antifreeze/coolant with water at about the maximum (65% antifreeze, 35% water) filled it up to about the max line and marked the level on the tank. One more question, assume it maybe a cracked radiator, should I start the car to let my new coolant mix, or leave it alone?
Either way I'm taking it to my mechanic to find out ezactly what it actually is tomorrow. Well, there you go thats my update, thanks for answering any of my questions.