1993 Probe SE headlights do not work!

I have a 1993 Ford Probe SE and my headlights have stopped working. When I try to turn on my headlights. The first click turns on the parking lights & interior instr. panel lights. The second click does NOTHING. The headlights pop up and the highbeams work ONLY if I drive with the headlamp switch pulled toward the driver & if I let go the headlights pop down & go out. Any suggestions??? Anyone know how to test this problem with a ohm's meter? Thanks.