The transmission fill is on the bottom - that drain plug you removed is a two piece plug, the inner section comes out and you put a tool from OTC ( http://www.amazon.com/OTC-6604-Trans...8116814&sr=1-1
) to pump fluid up into the transmission. You can do it with a ****** brass connector since you need to do it right away - take the plug down to Auto Zone or the like and find one that will screw in.
You will need to put a hand pump on a quart of transmission fluid bottle and pump it up into the trans. Keep doing it until fluid starts to come back out. Put the center plug back in and start the car up. Let it run for a bit, move it through the gears. Once it is warmed up, get back under the car (watch the hot parts!), put your filler back in the center and pump more fluid up until it starts to drain back again.
It will probably take about 7 quarts.
Ideally you pump fluid up into the trans while it is running, but if you are on jack stands that isn't a good idea. So take it to your friendly dealer and ask them to double check and top off the transmission.