How do you flush and fill a radiator for a 1998 Cadillac sedan sts on 1998 Cadillac Seville STS

What type of coolant do i use, what are the steps to follow in doing the flushing myself

Asked by for the 1998 Cadillac Seville STS
it would be easier to remove the lower hose, catch the coolant and dispose of it correctly.
change the thermostat as well. use dexcool coolant. do a 50-50 mix.