Follow that link and read at least the first 4-5 posts and you will know more than you ever imagined. I put up pictures of the sensors and their locations, as well as descriptions of how the system works.
It appears that you have an easy one - looks like the divider switch has been removed/whatever.

The divider switch/sensor is in the DRIVER's side. The passenger side has no sensor.


ONE THING, even if that divider sensor is bad/disconnected, the windows should go down when the "D" handle is turned. If the windows fail to go down, then the power top module is not powered up, the latch retainer switch in the frame is bad, or the Body Control module has a problem.

Again, go read the first several posts I made in that thread and you will understand.