Cool off engine. Pull lower radiator hose and drain into bucket. Remove cap on radiator. Remove thermostat from T-Stat housing on engine. Coolant will flow from engine and radiator to low point at radiator hose you pulled off earlier. Stick garden hose in t-Stat housing and open valve slowly. Water will flow into engine and into radiator then into bucket until discharge is clear.
Refer to your handy Fiero maintenance manual for proper refilling procedures. Hint: Fill from engine first........
PS: I know a bucket won't fit under car so use an appropriate container that will and dispose of spent coolant properly.
"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut