Connecting Car Audio Components to PC/TV

Hello all, I'm a new member - and I'm not exactly sure where I should post this question, or if I will get any responses to it!

As the title says, I'm interested in hooking up a subwoofer and a couple speakers from an old car setup for use with my computer, or with my television.
I'm more concerned with hooking the subwoofer up by itself, but any help would be great.

Here's the components I've found around my house:

1. Rockford Fosgate 10" Punch Subwoofer / RFZ1410 / 4 Ohms / 200 Watt

2. Pyramid Gold Series Subwoofer Electronic Crossover / Model CR-66

3. Pyramid Power Amplifier / 240 Max Power Watts / PB175 / 120W x 2 Channels (I have two of these amps)

4. Universal Installation Wiring Kit (Various gauges of wire and that kind of thing)

5. Stock Chevy Impala (year 2000) 6" x 9" Speakers / Unknown Watt / 4 Ohms

I've been trying to read up on this process, and I'm not entirely sure if I can (or need to) use the amplifier at all... I've found a computer power supply of 350W, which I hope will be able to run the subwoofer on its own. The problem is I don't really know how to convert the AC into DC for the 12V audio equipment. Also, I don't know how to hook up to various inputs (such as the RCA from my television, or 3.5mm from my computer?).

I was hoping to build some kind of enclosure to house all these components so I can carry it around from place to place. But right now I'm just trying to get my head around how to properly combine all these components into a working sound station.

Any help or tips would be great,
Thanks!