The drain plug in the torque converter is accessed through a gap (hole) in the bottom of the bellhousing. How this usually occurs in a shop situation is the car is raised up and the engine rotated by using a 27mm deep socket, usually a short 1/2" drive extension, and a long 1/2" drive breaker bar or long ratchet, The engine MUST be rotated ONLY clockwise, oriented at the front of the engine. If you go too far, DON'T rotate the engine backwards, go around again. It helps to have someone rotating and someone watching for the drain plug.
If you can't secure the proper tools, you can attempt to do this by having someone "bump" the starter with the coil wire disconnected to prevent the engine from starting. This is extremely frustrating, but patience will eventually prevail. Most critical to have a good "bumper" who won't crank it after you shout "Eureka!". Or if you have a remote start switch, this will work a little better that the bump method, as the bumping input is much shorter than using a second person on the actual ignition switch.
As long as I'm thinking of it, the ATF you used should have been DexronIII/Mercon, if you used the wrong stuff, you may want to go ahead and replace it all again, I would say go ahead and reuse the filter.
After you've drained it all, put in 3 quarts of ATF, then start the car and finish refilling with the engine running. It will take at least 6 1/2 quarts, on your car may be more like 7 or 7 1/2 total with everything drained out.