hi i have a 90 civic and i would like to know to things:
what kind of suspension do i have (mcpherson or 2wishbone on all fours)
and how to tune my suspension so the car rides as neutral as possible(in relation to cornering like little oversteer and understeer)

 

Civics from 88 to 00 are all double wishbone front and rear. It's a goddamned miracle. We're all eternally grateful. 01 went to mcpherson up front. The RSX is crap. Toyota Camry with Acura badges on it. 06 and up are also Mcpherson, though greatly improved from the 7th gen Civic and the RSX. You're gramma will just love it.

You tune your suspension through infinite track time and tire temps taken from a needle-style pyrometer. Get an adjustable rear swaybar like the Progress 24mm and a GSR or EK Si front sway. Don't go too crazy on the suspension though or you'll never learn. Stock suspension is the best to learn on but you want some slight adjustability too for experimentation (hence the adjustable rear sway). I would also suggest some adjustable camber upper rear arms but the upper front arms are tricky. It's very difficult to find a good brand, and they're all so expensive.

You'll need a book or a good forum to help you interpret the tire temps. But you'll need to find that on your own. It's miles away from Honda-tech. This is the forum for "how do I slam my ride" and "excessive negative camber doesn't hurt your street tires".