Instructions
Turn on your PlayStation 3 and log into your system account. You need an account registered for online use to download from the store. If your account is not registered, the system will automatically guide you through the registration process when needed.
Scroll the menu bar to the right to find the "PlayStation Network" column and go down to the "PlayStation Store" option. Press "X" to select it. The store will load and display various types of downloads.
Select the "Demos" button to view free trial editions of games. Check the "Add-ons" area for expansions for games you already own, some of which are free. Look under "Themes &Wallpapers" for downloads that change the appearance of the system menu. Go into the "Media" section for video clips.
Scroll through PS3 store listings in whichever section you pick. The price of the highlighted item displays in the information panel on the left side of the screen. Look for any file you want listed as "Free" and select it with the "X" button.
Read the item description that pops up and press "Download" to begin saving the file to your system. After the download completes, exit the store by backing out repeatedly with the "O" button and locate the file under the proper column on the PS3's main menu. Game add-ons will not appear on the system menu but will load automatically when you play the game that uses them.