Google's Android operating system uses an application called a Launcher to start apps and access settings. It's a lot like a the desktop on your computer -- but unlike your computer desktop, it's easy to install a new launcher app for Android. You can download a new launcher app from the Android Market; some popular alternatives include Launcher Pro, ADW Launcher and Zeam. If you want to change your already-assigned default launcher, you can do so in the phone's settings.
Turn on your phone and unlock the screen. Press the "HOME" button.
Tap the application drawer, then tap "Market." Press the "SEARCH" button.
Search for a launcher replacement. If you don't know any replacement launchers, try "Launcher Pro," "ADW Launcher," or "Zeam." Tap "Go."
Tap a free launcher in the search results. Tap "Install," the "OK." Wait for the app to download.
Press the "HOME" button. Tap the "Use as default" box, then tap the new launcher.
Press the "MENU" button, then tap "Settings." Tap "Applications."
Tap "Manage Applications." Scroll down and tap your current default launcher.
Tap "Clear default." Your default launcher is now reset.
Press the "HOME" button again. Tap the launcher you want to use, or tap "use as default" then the launcher to set a default again.