wanted to know how to do the green lines to design body kits could desir me?

First you need to know how to use the Pen tool. If you go to deviantart, google or youtube, simply type Pen Tool Tutorials.

When you know how to use it, choose a base picture like you would when doing a normal chop. Make a new layer, fill it with black and set the opacity to about 60%. Use the pentool with a 2px brush, and line up the body of the car. Make sure you have the brush colour selected to green (if thats what you want) Its also important you have the black layer and the lines on seperate layers. Then if you want to change some bodyparts, try to be creative and line them up yourself, Like new vents or something. If not you can paste new bodyparts to your car under the black layer. Make them fit as good as possible and then line over..

I hope this makes sense.

never really understood how to make a good chop from lines, got any good tuts or ways of explaining how to do it/interperate it?

Sometimes its easier to sketch up what you want. In this case you do it using pen tool on a black layer.

Its very useful if you're doing a full brush.

its basically this
http://zer0gfx.deviantart.com/art/Pen-Tool-Tutorial-153028718
but instead of clicking "make selections" select "stroke path" with a brush
make sure you set your px 1st tho

yeah using line first help a lot, at least they do for me anyway. I see them as a plan, so if you forget to add anything later on you just view the lines and everything you had planned shows up. Also, you get to see a preview of the final shape of the car including bodykit, interior, rims etc etc.

When I brush, which is rare anyway, I just do something. However, as you can see with my chops, I never do (and can't) do wild bodykits like jackdarton fx.

It helps because i'll rough brush and piece a kit idea together, then draw in lines on the car as new path trace lines so everything is in order and i can get a good green sketch of what it'll look like