1993 Ford Crown Victoria replacing headlight switch

Hi: This is somthing you should start with by checking out a library service manual for, unless you wish seek another source. To explain this here would most likely do you a mis service with out some common frames of reference.
Consider if you have not done so, making sure the switch is the problem. Look through the book before check out if you can, in some cases the better manuals are ref. only and can not be checked out.