That's a very vague question, and there's soooo many things to pick at, hopefully someone'll move this, but here we go.
First off, USE THE SEARCH FEATURE. you'll get it alot, but it's true, all of the basics have been verywell covered inhere. search is your friend, you'll learn everything you need to know and some stuff you thought you didn't.
Nowthen, There's 2 camps, and I'm sure someone from the other will speak up, but capacitors are prettymuch worthless, and really only introduce some serious potential for shocking the sh!t outta yourself. IN fact, depending on the type of use, they'r elikely to just create more draw. IN the end you're paying more money to use power that you've already got.
What kind of 1500W setup are you talking about? becuase I've had a Legit 1600W setup in my car for a year now and while it IS indeed possible, 1.5KW amps aren't cheap or easy to come by, and REAL 1000w+power is ALOT. What's the RMS rating?
Also, what sub and amp do you have? Be as specific as possible. Are they compatible impedance-wise (4ohm sub with an amp that will bridge to 4ohms, etc)
As far as wiring everything, if you're TRUELY clueless it might be your best bet to simply hav eit installed, but PLEASE run searches, it's been covered time and time again. also have a look at the FAQ in the audio section. It'll save yourself and everyone else alot of time and typing.