hey dont worry about it. the install itself is quite simple, i used bulldog, which gave me insructions about what to look for. you do all the wiring from the head unit, which can seem daunting, but once you get into it, it really isnt. what i did was make each wire that was being used for the installation with masking tape, and label them, then you just hook each wire up to the other, and voila. here's a link to the bulldog site, they have a wide variety for reasonable prices...also walmart sells bulldog pretty cheap too.
http://www.bulldogsecurity.com/ also, they give you what the exact color is for pretty much any car, which is very helpful...
http://www.bulldogsecurity.com/diagrams/diagrams.htm