Well I don't know if you have solved your problem already, but if not I'll try to explain how you update your bios.
First you just have to put the bios file on your USB flash drive.
Then restart your computer and during the booting process hit delete(Actually it depends on your motherboard which button you have to press. If you have the manual look there)
Then you get a screen where you can change many different settings of your pc. Depending on your motherboard the screen looks often different but here is an example of how this screen looks like:
Select the category boot and as you can see under the category boot you can change the order how your system boots. So you just have to put for example removable devices on the first place, cd-rom second, harddrive third... etc.
After that you just need to save the changes and exit which often is done if you press F10
That should solve your problem
ps: Yeah my first post^^