Use your PC/Mac to download an XMB theme to a USB device and then install onto your PS3.
Reference for the PS3 folder structure used on a USB removable device.
So you bought a PS3 but you still have Playstation 2 games that need finishing? We explain how to transfer your PS2 game saves using a Memory Card Adaptor.
Update the PS3 system firmware via PC and USB removable media.