You're a newbie to this car PC world and everyone seems to have way more skills with electricity than you? There are a few things you absolutely must know and here are a few links to tutorials on them.
1. Soldering: Main uses - connecting wires together extending existing wires, connecting power supply harnesses to your electrical system and so forth. This is the most foolproof way to connect two wires together.
Soldering tutorial: BoxGods.com video tutorial of soldering
2. Multimeter: A multimeter is absolutely indispensible for testing whether a wire has voltage in it (finding wires that your ignition turns on and off), how much power is flowing through a wire, or testing whether one part of a circuit is connected to another part (i.e. testing if a fuse has blown or not). Multimeters are intimidating if you've never used one, but relax - you don't need a very expensive one and you only need to figure out how to use one or two of the functions.
Here is a video on how to use a multimeter (thanks to user chanh55 for the link!): [MEDIA]http://www.youtube.com/watch?v=KzjMIcER4EU[/MEDIA]
Multimeter tutorial: How to from AcmeHowTo.com
Here's another that discusses the different types of multimeters
3. There's already a FAQ on finding wires in your car.
mp3car.com members, post your favorite skills links here. Try to keep them basic, just the ones you absolutely need to know.
And of course, if you're new, check out the FAQ Emporium if you haven't already.