Are you sure the antifreeze is blue?
Never seen blue.. red, green, super yellow... hmm
Well, find the radiator (right in front) there should be a hose that runs off to a tank on the side. On the tank there is a "fill" line. Might it say COld or Hot fill line... fill accordingly
If you had poured it into the washer fluid tank.. it wouldn't have overflowed... and if you poured winshield washer fluid in with antifreeze... well, hmm.. I would think it will evaporate quickly.
Jeez.. does it have pedals? I'm surprised it has an engine its so small! Lol ;)
Its got to be one of those "Tanks" look for one that SAYS coolant