headlights not working 1990 cutlass supreme

Ok, So I am a rookie--After extensive under the hood repairs (coil packs rad, plugs etc etc etc.) I cannot find the headlight relay, Theres is also a sensor that automatically turns headlights on when it is dark out. Can anyone direct me to where to find these components and possible reasons the headlights wont come on. Thanks much for your help!!

cutlass headlights