It isn't too hard to do luckily. You drain out the AFT that is in there now (there is typically two drain plugs on the Trans, one on the main pan below the valve block and one by the differential), fill it with new trans fluid and maybe some seafoam or AFT flush compound which cleans out the burnt out clutchpowder from the clutch packs, run that typically at idle for around 15 minutes to half an hour, drain that and put in fresh fluid. In all you may need 10 to 15 quarts of ATF for the two refills but it will clean it out pretty good.

__________________
2001 Chevrolet Monte Carlo SuperSport