parallel port input?

plz help me to, how can i receive signal or instruction from paralel port, how should i send current/signal to its register. what equipment should i need. actually i want to develope a system in c language to control electricity of home, doors or widows, so i need to check that if the door is open or closes. when door closed then computer should indicate me that the door is closed, and same door has opened. sir plz give me guideline. i would be very very thankfull to u. ( simply tell me how current/data/signal can be sent through parallel port, current source, equipment ets, after that i will make sensers for it my self)