I want to install an alarm for a Nissan car

Hi, can anyone tell me where I can find a website with an installation diagram for car alarms? My car is a 1998 Nissan Tsuru, and I have the original alarm, but the diagram doesn't show the model. I'd like to know where I can find a website with a simpler explanation. I'm looking for a more detailed diagram because there are some wires I don't know how to connect, as the printed instructions are in technical jargon. Thanks in advance.