Bios upgrade

How do I upgrade my bios
BIOS Date: 09/05/00
BIOS Type: Award Modular BIOS v4.51PG
BIOS ID: 09/05/2000-693-596B-977E-2A6LGP8JC
OEM Sign-On: 09/05/2000 DVAX2P FOR DVAX2+ / 6VAX2+ (Y2K READY)
Chipset: VIA 82C691 rev 68 for