Instructions
Determine what you would like to backup. If all you would like to save are "game saves," which are the files that tell your PS3 information like where you are in the game and how many points you have earned, then you only need to use a USB flash drive or an SD card to save them. If you also wish to save movies, photos, songs or game demos, then you probably need an external hard drive. To figure out how much data has been stored on your PS3's hard drive, go to "Settings," followed by "System Settings" and "System Information."
Insert your storage device into the PS3.
Backup all of your data by selecting "Settings," then "System Settings." Select "Backup Utility" followed by "Backup." Click "Yes" for both prompts--one that lets you know that your trophies will not be backed up, and one that asks if you want to backup your hard drive data to storage media. Highlight the device you want to store the data on (for example, "USB Device") and click "Enter" using the "X" button.
Backup game files only by navigating to "Game." Select "Saved Data Utility," then highlight the data you want to backup (which are organized by game title.) Press the "Triangle" button. Select "Copy" and highlight your destination (for example, "USB Device.") Click "enter" using the "X" button. Repeat this process for each game data you wish to copy.
Wait for your data to finish copying. Once it is complete, you will receive the message, "Copy completed."
Write down your PS3 network username and password, which you chose when you first connected your PS3 to the internet. Save this information in a safe place, as this information cannot be stored onto an external storage device.