So as radi8or says you go to the manufacturers website which is ECS click here and pick the download for the motherboard you have, make sure you pick the correct motherboard Bios instructions are on the site. I hope you realise that if you get it wrong you can make the motherboard unusable? Why do you think you have to flash the Bios to get your USB to work or to add more USB ports? You usually only have to flash the Bios when you're upgrading the processor or such like.
So flashing the bios wont make USB work. I thought that flashing the BIOS would make USBs work because I have an old system and added a USB pci card, it didn't work so i thought that it wasn't recognised in BIOs because it is to old. (1996 I think)