Decide what you'll use. I went with Redline MTL (
Manual
Transmission
Lubricant)
Find more about what I used here
So, get your stuff
Then lift up the car (in my case that involved cleaning up the bay so my tech would let me use his lift

)
Locate the transmission and drain plug
Unscrew the drain plug and drain all the dirty fluid out
Then, tighten the drain plug up, unscrew the fill plug and use a pump to fill the transmission back up with the new fluids.
Once you see it overfilling, you'r done, let the excess drain out, tighten everything back up, and call it a day
