How do you replace backdoor window on 2002 Malibu?

Remove the door panel first. Turn key to on position and roll window down (or bracket if glass is broken or missing) until you see both bolts through the access holes usually halfway down or somewhere in that vicinity. I believe they are 10mm bolt that hold the glass to the regulator. After unbolting bracket then (if there is an existing window glass) rotate the glass slightly working it out of the tracks and lift out. Don't force it or it can break, it will come out only one way and should be pretty easy to figure out. If no glass is present then just remove old pieces and insert new glass at an angle it will slide into one track then the other and work it down to the mount and replace bolts. Roll window up and down all the way several times to ensure proper functioning. If so replace door panel.