Unlike most Android phones, the HTC EVO 4G does not need to be rooted to take a screenshot. Instead, EVO 4G users must simply download a special application onto the device to enable the screenshot feature.
Tap the "Market" icon on the device's home screen. Tap the "Search" icon on the Android Market's main menu and enter "ShootMe" into the Android Market search bar. Tap the "Search" key to search for the application.
Tap the ShootMe application listing in the list of search results to view the application's details. Tap the "Install" button to install the application onto the device.
Navigate to the screen that you would like to take a screenshot of. Shake the phone vigorously for two seconds. The ShootMe application will now automatically take a screenshot of the device's screen.