Change dashboard background wallpaper osx lion

This will show you how to change the background wallpaper of the dashboard in osx lion.

open finder
goto /System/Library/CoreServices/Dock.app/Contents/Resources
find the file pirelli.png
rename it to pirelli_backup.png
copy the image that you want for the dashboard background to the folder and name it pirelli.png
find the file mini_pirelli.png
rename it to mini_pirelli_backup.png
copy the image that you want for the dashboard preview background in mission control to the folder and name it pirelli.png
the mini_pirelli.png file is 200×125 pixles
open terminal and type
```
killall Dock
```

now your dashboard will have a new background