1. First, you need Photoshop or Paint.NET (download it here).
2. Go to your CRC installation directory and find the folder vehicles.
3. Now, find the car, which you want to mod. For example Peugeot_206_GTI.
4. In there go to textures, then skins.
5. There are a lot of .DDS files. Open Paint.NET or Photoshop.
6. Click File, Open and go to the skins directory.
7. Open the skin and mod it!
8. When done it's recommended you click Save as... and not just Save, because the skin will overwrite then.
9. Enter any name you want and click save. Note: On some vehicles, there are template skins. You can use them for advanced texture making, like adding photos and stuff. If you have trouble with the skins, or they appear blank, post it here and I will try to help (again). Also, you can find some tutorials for painting and editing on Paint.NET here.
Important
-CRC loads automatically DDS and PNG files from skins folder,
-usually you need DDS filter for your own Photoshop, you can find here,
-CRC works with alpha channel, it must be white at the skin files (if it has),
-image size must be multiple of four
-use DXT3 set when you export in Photoshop (at the confirmation panel)
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