I'm quite irritated as to my car's sound insulation, it's a 95 corolla and I want to remove some of the outside noise when I'm driving, Are there ways I could use so as to lessen the external noise(engine noise,other vehicle's noise) from the cabin?
Yes, the normal route is to add sound deadening material inside the doors and/or on the floor of the car. A corolla won't have much stock insulation so you should be able to make some good progress in reducing it.
This is a common project for people who are installing nice audio systems, so you should be able to find some nice walk-throughs on audio sites.
you can try bitumen coated foil/carpet underlay/sound deadening paint (similar to under body paint)many solutions to be found at any auto parts store