Also, l wanna get some nice upgrades to give it a little better gas mileage, but also, make it nicer

it would say right on top of the engine

Go to carmax.com and type in your VIN number and it will tell you exactly what the car was sold as, after market mods probably wo not be shown, but it sounds like you would not know what those are anyways.

When you open the hood on your car you will see the letters VTEC also SOHC or DOHC.

all Honda motors with vtec have vtec written on the valve cover, for better gas mileage u just gotta do all the maintance on ur car and check ur tires air pressure. I/H/E will make it nicer not better at gas mileage.

It should say V-tech on the engine and on the side of car.

its only dohc if it is a si. And its a honda it has some type of vtec

Usually on the engine itself it will note if it is a VTEC engine or not.
In ur case:
D17A2

* SOHC VTEC
* Found in:
o 2001-2005 Honda Civic EX
o 2001-2005 Honda Civic Si (Canada only)
o 2001-2005 Acura 1.7 EL (Canada only)
+ Displacement : 1668 cm³
+ Bore & Stroke : 74.98 mm X 94.4 mm
+ Compression : 9.9:1
+ Power : 127 hp 5800 rpm & 114 ft·lbf 4800 rpm
+ Valvetrain : SOHC VTEC (Single Cam)
+ Fuel Control : OBD-2 MPFI

it is a SOHC VTEC engine.

Try:
http://andysautosport.com/honda/2001_2003_civic/
to see a good bit of the options available for a 7G (2001-2005) Civic