Lowering?

The new Motegi MR7s in gunmetal are now on the car.
But it needs lowered badly. So i need some help. What is the difference between springs and coilovers (or is there one?). Also for a 96 civic coupe with 17s how much should i lower it? I do alot of driving. Anything else that i need to know would be great.

Also this guy told me i could do it myself and its not really hard. But i am kinda sceptical about that. How hard is it really?
thnx everyone
Ill post pics of my rims on the car once i find a camera.