Mac OS X Lion, Apple's eighth major release of Mac OS X, included a new feature called Mission Control. Mission Control combines Dashboard, Expose, Spaces, and Full-Screen apps into one, easy-to-view screen. In general, Mission Control has received mixed opinions from upgraders - some say that it's great, while others say that it's too cluttered.
One complaint that users have of OS X Lion is its use of linen-based wallpapers (like the one found when entering Mission Control). Many would like to change this background to something more unique and elegant. Luckily, with a little modding, you can change the wallpaper of Mission Control. Here's how to do just that:
Step 1: Find the resolution of your display. To do this, open System Preferences (Applications>System Preferences or Apple menu>System Preferences). Click on the "Displays" preference pane and look at which resolution is currently applied to your display.
Step 2: Find the background that you'd like to use. It can be anything - a nice wood wallpaper or the same one you're using for your regular desktop(s) on Lion. Open the image up in a photo editor (for example, Photoshop) and resize it to match the resolution of your display. It may be easier for some of you to find an image that is the exact resolution of your display from the beginning, as you may not have access to a photo editor with resizing capabilities. Save the resized image to your desktop, making sure that it is in .PNG format and named defaultdesktop.
Step 3: Navigate to the following directory via Finder: /System/Library/CoreServices/Dock.app. Right-click on Dock.app and click "Show Package Contents." Then, navigate to: Contents>Resources. Find the image called "defaultdesktop.png" and re-name it to "defaultdesktop-old.png."
Step 4: Drag-and-drop the image that you saved to your desktop into this folder. You may be asked to enter your password - make sure you do so correctly.
Step 5: Once the image copied into the folder, open Terminal (Applications>Utilities>Terminal) and type in the following command exactly as it appears: killall Dock. You should notice your Dock disappear and the background of your desktop go gray for a few seconds.
That should be it! Enter Mission Control and you should have a new background for it!