auto seat belts!

i need some help…i bought a 91’integra GS…and the auto seat belts weren’t working so i came up this awesome site…i found out about this “silverish box” that controls them… so i went in and there was a green plug about an inch wide unplug so i plug it in…my driver side belt works now…but the passenger duzn’t…its plugged in and the plug underneath in connected as well…PLease help.

also, i noticed something wen i went back to look at that silver box again… and there is a smaller gray plug that isn’t plug into anything jus sitting there all alone…and i dont see or feel a place where it can go???