Foxconn may be a little tricky, but typically you visit the website for the page with the drivers for your motherboard, and download the bios. Then you'll save this to a floppy, or more likely now a thumb drive.
Consult your motherboard manual. Updating the BIOS is VERY tricky and could cause permanent damage if done incorrectly. BIOS updating is an advanced technique that should approached with extreme caution.
Depending on your board, there may be a couple of options for bios updating. One is to restart the pc, enter the bios and on the last page or so listed it should have an option for bios flashing. Some motherboards have a special startup keystroke to enter the flash utility during post. Either way, be sure to follow the directions precisely or you could possibly brick your entire machine.