On the right side of the trans casing is a large screw, that's where the oil goes in...but we'll get to that in a moment.
On the underside is a similar screw or bolt - put a drain pan under there, and remove it...that'll drain the works.
On the side is a flathead screw with a paper washer under it, that's a level check screw, useful to remove that as well to avoid overfilling.
Now, Dexron ATF is what goes in there, 220cc's worth of it, but I would "flush" it a bit first - it's hard to get it in that little hole at the top, so try using a straw, a funnel, and some tape - you'll figure it out.
After flushing, replace the bottom screw/bolt, and fill till it begins to dribble a bit from the level check screw hole - then put that screw back in, and the top one, and yer all done.
Pretty simple, other than getting it in that damned teensy gole.