Headlight Adjustment

I have an '04 Sienna XLE and I constantly have oncoming drivers flashing their brights at me because apparently my headlights are aimed a little too high. Truth be known, they are, because I've had my wife follow me in the van and the lights really are annoyinh.

Can I adjust the level myself? I checked and there is what appears to be an adjusting screw with teeth around a collar on the back of each light assembly. Since I see no other obvious means of changing the level, I'm wondering if that's the trick. I'd hate to have to pay some 'technician' just to adjust my headlights. Thanks for any help.