Firstly ofcourse, you have to have paint.net. You can download it here:
Paint.NET Download

Now you have this installed you need the plug-in. This enables Paint.net to open Photoshop type files (.psd) The Plugin is downloaded here:
Photoshop Plugin Download

Unzip that file and put it here, i am on Windows XP so for Vista it might be a bit different:
C:\Program Files\Paint.NET\FileTypes
Now its in that folder, you can "re-open" Paint.NET and use the open function to open the Template file for Photoshop. Which is here:
Photoshop Template Version

Now, using the Layers option in the bottom right hand corner on your screen you can turn the renault logo, cockpit and shadow effects off, this leaves you able to create your design and then re-apply these effects later to give a good 3D and real lighting effect.

Thanks to mikiyaru for the info!