Files, including music and movies, can be transferred to a PlayStation 3 using either an external hard drive or an Internet network. Though transferring files with a wireless Internet connection may be less of a hassle, an external USB hard drive is usually faster. The PS3 is equipped with high-speed USB 2.0 ports. An external hard drive can either be plugged in and left in place, or used temporarily to transfer files to the PS3's Internet storage drive.
Connect the external hard drive to a computer with the USB cable. Click "Start" on the desktop menu, then choose "Computer." Right-click on the external hard drive listed under "Removable Media." Choose "Format" from the menu. Click on the drop-down box in the format prompt that appears and choose "Fat32." Click on the next drop-down box in the prompt and choose "Quick Format." Press "OK." This formats the hard drive to the necessary file system for the PS3; back up any data on the hard drive before continuing.
Disconnect the external hard drive from the computer. Plug it into one of the PS3's USB ports. Connect a PlayStation controller, then turn the PS3 on if it isn't already.
Navigate through the PS3's menu for the item titled USB Device. Press the "Triangle" button on the controller to open the external hard drive and browse the files. Select the file you want to transfer, then select "Copy" from the list. This transfers the selected files to the PS3's internal hard drive.
Disconnect the external hard drive when finished.