you can download one for free around here somewhere.
allsentra.com/fsm/ also has them online
if you look up from the passenger floor, normally where the passenger feet are, and look up into the dash towards the middle of the car, youll see your blower resistor. get another one so you can see what it looks like. it has an electrical harness going to it, and is held on with 2 screws. once you remove the screws, the card will slide out, just replace with a new one.