some nice person has deceided to drag something sharp down the drivers door of my car about 5 inches long!

bastid
now I've used bodyfiller to fill the scratch all rubbed down and ready to paint.
I know the basics of painting not done much. I have just got an airbrush which can be used for automotive touch ups, which I want to use for this.
The scratch is near the winow going vertically own, hopefully I can blend it in.
The colour is reflex silver.
Now I'm thick when it comes to paint here. Where do I get the exact colour paint I need. I gather I need a primer, basecoat and lacquer. Also thinner.
Is there just one type of thinner I will need to thin the primer, basecoat and lacquer own ? or is there specific ones for lacquer ?
I would use chipsaway but I cant afford there fees, last time I used them I got some minor things but in all fairness quite a few costed around £300 so fair enough. I remeber the dude used a airbrush actually.
What brand of paint do I use so many to choose from ?
any advice is deinfitely welcome as I'm a newbie in this area.

Cheers
