Meant for Q&A but ok i gotchu.
You gotta win races to win points.
1rst = 3points
2nd =2points
3rd =1 point
And these points can be used to upgrade your cars.
You might wanna look into some guides but what i followed was
Dont upgrade your E class cars. Use the Volvo 850 or the Civic to win as much as u can (only weight reduction upgrades if you're not winning) and farm points till u reach D.
Once u reach D , u upgrade a car with those points then race with that throughout D class and farming for C class and so on till you reach A.
The cars i used are
E - Civic
D - Toyota MR2
C- corvette
B- Mustang
(i might have intechanged C and B , dont remember the class , im travelling )
A- started with NSX
Many people would say the Sierra for B and honestly thats true but I couldn't afford a seirra back then so i didnt really use it.
Guide for when you reach A class
I think this guide also have a guide linked for new guys too.
RD's racing guide