jack the car up, secure it with jack stands or something sturdy, then 1st loosen the fill hole on the right side of the transmission, you use a regular 3/8 inch ratchet. then loosen and remove the drain plug below it. make sure the fill hole comes loose first, so you can re fill it. sometimes they strip out, so go easy when u tighten them, snug is enough. i'm using the amsoil synthetic fluid in my t-5-z and love it.
Be sure the car is relatively level before refilling. After draining, replace the drain (lower) plug, but leave the fill plug out. You can pump into the fill hole, or you can remove the shifter plate and pour into that opening from inside the car. It should take about 2.7 quarts at which point the fluid should just start coming out the fill hole (upper hole) on the side of the tranny. That's how much fluid you want in it. 3 quarts should leave you with a bit left over.
If that's how you choose to fill it. I prefer not to have any open container with atf in my car as I'll spill it on the carpet for sure. I use a small ($9) hand pump bought at Autozone that screws directly on to the quart bottle of fluid - just pump it right in the fill hole from underneath until it begins to just run out of the fill hole (2.7 qts.). Alternatively, atf is thin enough, you can run a piece of hose into the fill hole, and snake it up the side of the tranny under the hood. Put a funnel into the end of the hose, and SLOWLY pour your atf in. Just be careful - easy to make one helluva mess.