Not bad for a freebie!
What headunit do you have?
Unless your Dad gave you it, you need to go buy a wiring kit.
It'll have the power cable with fuse (goes from the battery to the amp), an RCA cable (goes from headunit to amp, send the audio signal), a remote cable (tells the amp to turn off when the headunit is off) and speaker cable to go between the amp and sub.
Make sure the level/gain on the amp is all the way down or you'll kill something.
cool il buy that tomorow, would it be better to have a different head unit