How do you replace a heater core in a 1990 Chevrolet Corsica?

it is located under the dash in the middle right on top of the frame or trany hump there is a black case on the outside with if I rember right 4 screws holding on to the heater core case them the should be 4 to 6 screws to take the 2nd plate off at theis point if you hace big hands or larger arms call closest friend cheapest help to crawl under car and take of the spring hose clamps or possably hose clamps befor you start all this you should have drained the coolant take both hoses loose the go back to under the dash and there should be 2 core brackets holding the heater core in eith 4 screws try to rember which way it came out to you can get the new one back in put back together in oppsite order make sure you use new heater core hose clamps