<font color='#000000'>This really isn't the best place to ask about Car audio installation, I'd recommend SoundDomain.com for that....but since I'm a nice guy and you sound like you can really use some help I'll tell you what I know.
The long of it:
First thing you need to know is the power rating in RMS of your sub. It will be listed in watts. This will help you determine the necessary wattage you will need for your amp. Generally the more watts you need the more expensive the amp. Stay away from brands you've never heard of, as many times these are garbage ie. stuff you might find in JC Whitney catalogs that claim big watts but are truly crap. Alpine, MTX, Fostgate, Eclipse, are all good brands.
Once you determine what amp you want to use you'll need to know whether your head unit (the radio) has preamp outputs(little round holes that rca cables plug in to) or only speaker outputs (just wires for each speaker).
If BOTH your head unit has preamp outputs and the amp you bought (recommended) has line level inputs then run a long length of decent quality rca cable to your trunk or wherever you're mounting your amp and then hook it to the amps rca line level inputs.
If you have only speaker outputs you'll need to tap in to the + and - of the right and + and - of the left front channels coming out of the back of the head unit with some speaker wire. Then run each speaker wire to the amp location and connect it the wires to the proper speaker level inputs of the amp
Next you need a power connection to the battery. Usually people just run a 12 gauge wire directly to the battery then run the wire through a grommet somewhere on the firewall of the car. Connect the power wire to the proper input on the amp. You may want to get a new battery terminal that can accomodate the added wire and a power distribution block with a fuse. You can get them at Autozone and other such stores.
Also you need to find and tap the accessory power line. This sometimes hard to find wire will allow your amp to be controlled by the accesory on/off switch that accompanies the turn of your key. This way the amp will turn off when you turn off the vehicle, otherwise it would remain on and drain your car's battery and leave the amp on all the time. The wire, once you've tapped it correctly, will connect to the amp and it will be the smaller of the two power connection labled switch or something like that.
Lastly run speaker wires from the outputs of the amp to your subwoofer.
The short of it:
Buy an amp hook up kit at Best Buy or Car Toys or other car audio installation shop and follow the directions very, very closely.
Hope this helps. And please remember to repect others when you drive round bumping away by eliminating external vibrations with damping material (available at the same places you find amp hookup kits) I hate nothing more than the sound of some morons trunk and liscense plate rattling.</font>
