Go back to the MB webpage and look for the flash program particular to your MoBo to download. The flash programs are specific to the MoBo chipset. Usually, to flash a MoBo you have to boot from a system disk floppy which contains the flashing program and the new BIOS file. The procedures vary slightly between manufacturers so you should follow your MoBo's manufacturer's procedure to the letter. Otherwise you could end up with a corrupt BIOS from a failed flash. Which is not easy to recover from.
It is hard to predict if a later BIOS revision will increase performance or not as BIOS revisions address different issues within previous BIOS revisions. If you are happy with the way your computer is running do not flash it(ie. If it ain't broke don't try to fix it).