How to change heater core?

copy and paste the link below,has detailed instructions with pictures...this is a paid site,BUT you don't have to pay,someone else ask the question,so it's still posted..when the screen turns dark,just click on the drop down menu on lower right,screen will turn bright again.. how do you replalce a heater core in a 1996 pontiac grand am www.justanswer.com/car/...replalce-heater-core-1996-pontiac-grand.html