[gta mod installer does not work?]

ok so ive tried to install a lambo countach and a r33 with this program but when i start game, the cars havent changed..whats wrong?

[where to find the car files]

wow im stupid haha thank you very much. now i can mod..but one more question, the img tool for SA..is it compatible with VC too? or is there a VC img tool also?

[where to find the car files]

ok so the modding guideline above is helpful but what i need help with is where the files are to replace (eg. infernus.txd or .dff)

can someone tell me step by step where i go ? i really wanna mod cars