With your transmission hot and in park and with the engine running pull the transmission dip stick and wipe off the fluid with a clean rag. Then put the dip stick back in the tub all the way down, then remove and look at the fluid level.
If it'* a little low you will need a clean funnel. Place that funnel in the dip stick tube and then pour only GM approved transmission fluid in to the funnel. Only add a little at a time if your level is just a little low.
Then wait a few mins for the fluid to finish draining down the tube. Then check the level again. Add more if needed. Add until fluid is between the holes.
Check transmission fluid and top off
