Generally, the manufacturer will have information on howto install bios updates but it usually follows this:

1. download bios update
2. double-click on update file and it will ask for floppy
3. put floppy into the floppy drive (usually appears as A: in Windows)
4. update will copy necessary information to floppy.
5. when done (that's when the little light goes out) reboot the machine with the floppy in the floppy drive. It will update the BIOS. It is often CRITICAL that you do NOT lose power or interrupt the update (great way to toast your BIOS -- I've done this).

So, go to the manufacturer website and RTFM.