Instructions
Insert a USB flash drive or external drive into your computer. Click "View All Files" when prompted.
Open the folder where you store your music. Click the music files and drag them into the folder containing your USB files. Wait as the files transfer. Depending on the number of files, this can take several minutes.
Remove the USB drive from your computer. Insert it into a free port on your PlayStation 3. USB ports on the PlayStation 3 are in the front.
Turn on your PlayStation 3 and log in to your PSN account.
Navigate to the "Music" menu and select the listed music to listen to it.