How do I flash my bios?

Easiest way on Linux is to use a flash drive and usually put freedos on it and the bios file.
Then boot that. You need to know little dos so you can navigate to the file correctly.
I found unetbootin to be pretty easy to install a functional freedos with.

Of course the overall easiest method is to be using Windows.
The file is usually executable from within windows without all the hassle.
(Blame that on the wayward support hardware vendor give to linux)

Beyond that, without knowing much about the hardware at hand I can only point you towards this page:
https://help.ubuntu.com/community/BIOSUpdate

If nothing more, I hope it's a good starting point.

Good luck, in which ever direction you go.