The preferred method is to flash your BIOS using the DOS interface. To accomplish this:
1. Determine which way is supported (floppy or USB)
2. Download the BIOS update to the media determined in step one.
3. Restart computer
4. If you saved the BIOS update to a floppy, it will load automatically. If your BIOS supports updating from USB, you must enable the option to boot from USB first.
Generally, the update is an automated process, but you likely have to confirm the update before the said process begins.