Adding Powered Devices to your Car

So I got this new car mounting device for my car to hold my phone/PDA. It is a very clever device, and wanting something that is a little more permanent, I opted for the straight wired device. The problem is, I don't know the first thing about adding a new powered deivce to your fuse box. This thing only draws 1-2 amps, but I have no idea how to add it. I tried searching the web tonight, but didn't find much. In fact, everything I found had more to do with replacing your stereo. So where does one find such a thing?