This video shows where the backgroud images are stored on OS X. For Ubuntu and Window you can skip the part of right clicking and opening the package file. Just look in the file structure for the same directories and swap out the images. You MUST keep the names the same. They are…
background1.png – opening screen
background2.png – race screen
background3.png – settings screen
ClockSkin.png – image that shows on the clock face
The cheering crowd image will always show on top of your background on the startup page. This is by design to keep a little branding in place. Enjoy and happy skinning. Please share a screen shot of you own custom skins. I would love to see how you have customized your version of GFX.