First off

to TFS! I hope you enjoy yourself here.
Check the knobs that keep your taillights and filler panel in to be sure they're good and tight. Sometimes they back off some and then when it rains and the water runs down along the underside of the hatch lid and then down behind the taillights the water will come in through those holes.
About the only way I can think of to adjust the hatch lid some is to take those two "knob" looking rubber parts on the underside of the hatch lid and turn them in some. I can't remember right now which way that is. But those help adjust the rear height part of the hatch to help it seal better.
But what you might want to do is this. Get a friend to go with you and go to a self service car wash. While one of you stays inside the car in the back seat so you can get a good look in the hatch area, the other one takes the pressure wand and slowly sprays the heck out of the hatch lid and the taillights and filler panel using the high pressure spray. 9 times out of 10 you can see where the water is coming in doing this.
Good luck.
Oh and if you could please, can you go to the New Members forum and make a post introducing yourself and telling us a little about your car. Thanks!