How to Put a Subwoofer In My Car?

I have a 2007 ford falcon boyfriend mk ii station wagon, would anybody tell me how o but a Sony Xplod 12" sub in.

No different than any other car.

http://www.wikihow.com/Wire-an-Amp-to-a-Sub-and-Head-Unit

Amneet, the installation involves electrical and physical; The electrical part involves taking a prepared audio signal from the source- the stereo- and playing it into a speaker. In this case the speaker is designed to play bass in the lowest range of human hearing. Since these frequencies need a lot more power to reach the same loudness of the higher frequency speakers in the system, the sourced signal is usually amplified. There will be instruction specific to whatever amplifier you choose and it will need a power supply sufficient to operate it as it produces its amplified output; if you want 500 watts out, you need 500 watts to run it. This answer is getting too long already, so at this point it's better to refer you to a website which gives the detail you need.

The physical part involves mounting the subwoofer in a properly configured and sturdy cabinet and you can read detailed descriptions concerning that in this site; "the12volt.com". You will, of course need to consider the space in your car as you choose your cabinet and decide whether or not it fits. Your very short question does not have a short answer. Good luck. Better you should go to a stereo shop and pay them to take the pains to install what you want.