Lesson one..
A car has four wheels? He he... :P (unless you mod it of course.. )
A car has a steering wheel?
Okay, I'm just kidding.
Well, you yourself know the scope of it, so why ask a general question? You should be more specific.
Your Civic 2.0 is a crippled K20A. The powerful version of the K20 engine is in the DC5. That's why you get measly 155hp compared to the one in the DC5 at 200hp (more or less).
You can add intake and exhaust upgrades for power, some suspension to reduce body roll, and some rims and bodykit for bling.
That's where you might need to reseach, as in what kind of part do you need, or not need.
Or you could just keep it stock, and drive it as it is. One thing I can tell you to avoid is audio installs, esp in a shop where they say they can do it within one hour or so.
The newer systems all have integrated wiring harnesses, and some not so reputable audio shops will make a mess of your wires.
Well, if you ever suffered electrical gremlins in a NEW car, you'd know why I totally AVOID accessory shops.