OK
1st problem answer: Extract it to somewhere easy to find. i.e. My documents or your desktop
2nd problem answer: Right Click on and select "properties" from the list that comes up then untick the read only box on the window that should appear.
3rd problem answer: Hit F2 (i think , or just go upto "edit" and select "find") then type in the origional car name e.g. Sultan, Uranus, Infernus, Mesa, Sandking, Admiral. Then change it, save and quit, then put it back where you 1st got it from BUT DON'T RE-TICK READONLY.!