How do I replace a starter on 2000 pontiac grand prix 3.1 engine?

Disconnect the battery cables.
Raise and suitably support the vehicle. Safety is paramount.
Remove the front lower air deflector panel.
Remove the torque converter covers to gain accessc.
Remove the two cables (one large and one small)
Remove the two bolts that secure the starter motor to the engine block.

Attachment 8115

Clean the surface where the starter attaches.
Reinstall in the reverse order, making certain the battery and the cable ends are cleaned and tightened.

I hope this helps.