Language Keyboards in Mac OS 10.2 - 10.8
1. Open System Preferences by selecting it from the Apple menu or clicking on its icon in the Dock.
2. Select Language & Text<> from the System Preferences menu.
3. Select the Input Sources tab .
4. Check the box next to the language keyboard you would like to turn on. If you would like to use the on-screen keyboard, check the box next to Keyboard & Character Viewer.
5. To switch back and forth between languages, select the language you would like to use from the Input menu in the menu bar. The Input menu displays the flag representing the language you are currently using.
6. To view the onscreen keyboard, select Show Keyboard Viewer from the Input menu.
7. The German on-screen keyboard looks like this: