where is drain and filling plug of automatic transmissin fluid

If your vehicle has a drain plug for the automatic transmission, it will be located in the transmission pan, which will be obvious underneath the vehicle as it is a flat pan, with lots of bolt holes around it, unlike the oil pan, which typically has a deeper "sump." The fill area is through the dipstick tube on top. However, I recommend having a mechanic machine-flush the transmission. I used to do the fluid and filter change myself, but when doing that, you're only getting about 1/4 of the dirty fluid out. A machine flush replaces 100% of the fluid and I noticed a huge difference in my car after I had one done. It only cost about $100 and was well worth it in my opinion.