@thomastrouble , you are in trouble. If you have any idea what you are listening too, trying to EQ a sub without it's calibration microphone is a nightmare. Second issue is that one sub is never enough. The minimum is two. But, have at it. It will be a fine learning experience. The sub connects to your preamp then the R/L outputs go to your amp, a very fine one at that. Then, start twisting knobs and listening. With a properly integrated sub woofer system the subs should seem to disappear until a real low note comes along. If you hear the subwoofer as a distinct entity you have more work to do.
If you want to do this right for less get kits from Parts Express, a bass amp and a digital two way crossover with bass management like a MiniDSP. Do not use a plate amp. Get a commercial sound reinforcement amp like a QSC.